954 research outputs found
Robust semicoherent searches for continuous gravitational waves with noise and signal models including hours to days long transients
No full textThe vulnerability to single-detector instrumental artifacts in standard detection methods for long-duration quasimonochromatic gravitational waves from nonaxisymmetric rotating neutron stars [continuous waves (CWs)] was addressed in past work [D. Keitel et al., Phys. Rev. D 89, 064023 (2014).] by a Bayesian approach. An explicit model of persistent single-detector disturbances led to a generalized detection statistic with improved robustness against such artifacts. Since many strong outliers in semicoherent searches of LIGO data are caused by transient disturbances that last only a few hours, we extend the noise model to cover such limited-duration disturbances, and demonstrate increased robustness in realistic simulated data. Besides long-duration CWs, neutron stars could also emit transient signals which, for a limited time, also follow the CW signal model (tCWs). As a pragmatic alternative to specialized transient searches, we demonstrate how to make standard semicoherent CW searches more sensitive to transient signals. Considering tCWs in a single segment of a semicoherent search, Bayesian model selection yields a new detection statistic that does not add significant computational cost. On simulated data, we find that it increases sensitivity towards tCWs, even of varying durations, while not sacrificing sensitivity to classical CW signals, and still being robust to transient or persistent single-detector instrumental artifacts
Robust semicoherent searches for continuous gravitational waves with noise and signal models including hours to days long transients
No full text[eng] The vulnerability to single-detector instrumental artifacts in standard detection methods for long-duration quasimonochromatic gravitational waves from nonaxisymmetric rotating neutron stars [continuous waves (CWs)] was addressed in past work [D. Keitel et al., Phys. Rev. D 89, 064023 (2014).] by a Bayesian approach. An explicit model of persistent single-detector disturbances led to a generalized detection statistic with improved robustness against such artifacts. Since many strong outliers in semicoherent searches of LIGO data are caused by transient disturbances that last only a few hours, we extend the noise model to cover such limited-duration disturbances, and demonstrate increased robustness in realistic simulated data. Besides long-duration CWs, neutron stars could also emit transient signals which, for a limited time, also follow the CW signal model (tCWs). As a pragmatic alternative to specialized transient searches, we demonstrate how to make standard semicoherent CW searches more sensitive to transient signals. Considering tCWs in a single segment of a semicoherent search, Bayesian model selection yields a new detection statistic that does not add significant computational cost. On simulated data, we find that it increases sensitivity towards tCWs, even of varying durations, while not sacrificing sensitivity to classical CW signals, and still being robust to transient or persistent single-detector instrumental artifacts
Line-robust statistics for continuous gravitational waves: safety in the case of unequal detector sensitivities
No full textThe multi-detector F-statistic is close to optimal for detecting continuous gravitational waves (CWs) in Gaussian noise. However, it is susceptible to false alarms from instrumental artefacts, for example quasi-monochromatic disturbances ('lines'), which resemble a CW signal more than Gaussian noise. In a recent paper [Keitel et al 2014, PRD 89 064023], a Bayesian model selection approach was used to derive line-robust detection statistics for CW signals, generalising both the F-statistic and the F-statistic consistency veto technique and yielding improved performance in line-affected data. Here we investigate a generalisation of the assumptions made in that paper: if a CW analysis uses data from two or more detectors with very different sensitivities, the line-robust statistics could be less effective. We investigate the boundaries within which they are still safe to use, in comparison with the F-statistic. Tests using synthetic draws show that the optimally-tuned version of the original line-robust statistic remains safe in most cases of practical interest. We also explore a simple idea on further improving the detection power and safety of these statistics, which we however find to be of limited practical use
Search for continuous gravitational waves: Improving robustness versus instrumental artifacts
No full textThe standard multi-detector F-statistic for continuous gravitational waves is susceptible to false alarms from instrumental artifacts, for example monochromatic sinusoidal disturbances (lines). This vulnerability to line artifacts arises because the F-statistic compares the signal hypothesis to a Gaussian-noise hypothesis, and hence is triggered by anything that resembles the signal hypothesis more than Gaussian noise. Various ad-hoc veto methods to deal with such line artifacts have been proposed and used in the past. Here we develop a Bayesian framework that includes an explicit alternative hypothesis to model disturbed data. We introduce a simple line model that defines lines as signal candidates appearing only in one detector. This allows us to explicitly compute the odds between the signal hypothesis and an extended noise hypothesis, resulting in a new detection statistic that is more robust to instrumental artifacts. We present and discuss results from Monte-Carlo tests on both simulated data and on detector data from the fifth LIGO science run. We find that the line-robust detection statistic retains the detection power of the standard F-statistic in Gaussian noise, while it can be substantially more sensitive in the presence of line artifacts. This new statistic also equals or surpasses the performance of the popular F-statistic consistency veto
Bibliotheca Lampadiana sive Catalogus Exqvisitorum tam Historicorum quam Juridicorum Librorum, Qvi D. 28. Junii 1723. ... In Taberna Libraria, Qvam Wolffenbvttela habet, publico Auctionis ritu distrahentur à Jo. Christoph. Meisnero
No full textElectronic clinical decision algorithms for the integrated primary care management of febrile children in low-resource Settings : review of existing tools
No full textBACKGROUND
The lack of effective, integrated diagnostic tools poses a major challenge to the primary care management of febrile childhood illnesses. These limitations are especially evident in low-resource settings and are often inappropriately compensated by antimicrobial overprescription. Electronic clinical decision algorithms (eCDAs) have the potential to close these gaps by guiding antibiotic use and better identifying serious disease.
AIMS
This narrative review summarizes existing eCDAs, to provide an overview of their degree of validation and to identify gaps in current knowledge and prospects for future innovation.
SOURCES
Structured literature review in PubMed and Embase complemented by Google search and contact with developers.
CONTENT
Six integrated eCDAs were identified: three (eIMCI, REC and Bangladesh digital IMCI) based on Integrated Management of Childhood Illnesses (IMCI); four (SL electronic iCCM, MEDSINC, electronic iCCM and D-Tree electronic iCCM) on Integrated Community Case Management (iCCM); two (ALMANACH, MSFeCARE) with a modified IMCI content; and one (ePOCT) that integrates novel content with biomarker testing. The types of publications and evaluation studies varied greatly: the content and evidence base were published for two (ALMANACH and ePOCT) and ALMANACH and ePOCT were validated in efficacy studies. Other types of evaluations, such as compliance and acceptability, were available for D-Tree electronic iCCM, eIMCI and ALMANACH. Several evaluations are still ongoing. Future prospects include conducting effectiveness and impact studies using data gathered through larger studies to adapt the medical content to local epidemiology, improving the software and sensors, and assessing factors that influence compliance and scale-up.
IMPLICATIONS
eCDAs are valuable tools that have the potential to improve management of febrile children in primary care and increase the rational use of diagnostics and antimicrobials. Next steps in the evidence pathway should be larger effectiveness and impact studies (including cost analysis) and continuous integration of clinically useful diagnostic and treatment innovations
Synthesis and characterization of homologous nickel(II) and palladium(II) complexes with biphosphine monoxide ligands Ph2P(CH2)nP(O)Ph2 (n = 1–3) and pTol2P(CH2)P(O)pTol2
No full textA series of cationic nickel complexes [(η3-methally)Ni(P∧P(O))]SbF6 (1–4) [P∧P(O) = Ph2P(CH2)P(O)Ph2 (dppmO) (1), Ph2P(CH2)2P(O)Ph2 (dppeO) (2), Ph2P(CH2)3P(O)Ph2 (dpppO) (3), pTol2P(CH2)P(O)pTol2 (dtolpmO) (4)] has been synthesized in good yields by treatment of [(η3-methally)NiBr]2 with biphosphine monoxides and AgSbF6. The ligands are coordinated in a bidentate way. Starting from [(η3-all)PdI]2 the cationic complexes [(η3-all)P∧P(O))]Y (8–14). [P∧P(O) = dppmO, dppeO, dpppO, dtolpmO;Y = BF4, SbF6, CF3SO3, pTolSO3] were synthesized in good yields. The coordination mode of the ligand is dependent on the backbone and the anion, revealing a monodentate coordination with dppmO for stronger coordinating anions. The intermediates [(η3-all)Pd(I)(P∧P(O)-κ1-P)] (5–7) [P∧P(O) = dppmO (5), dppeO (6), dtolpmO (7)] were isolated and characterized. Neutral methyl complexes [(Cl)(Me)Pd(P∧P(O))] (15–18). [P∧P(O) = dppmO (15), dppeO (16), dpppO (17), dtolpmO (18)] can easily be obtained in high yields starting from [(cod)PdCl2]. For dppmO two different routes are presented. The structure of [(Me)(Cl)Pd{;Ph2P(CH2-P(O)Ph2-κ2-P,O};] · CH2Cl2 (15) with the chlorine atom trans to phosphorus was determined by X-ray diffraction
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