161 research outputs found

    Bayesian Estimation Of Performance Measures Of Cervical Cancer Screening Tests In The Presence Of Covariates And Absence Of A Gold Standard

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    In this paper we develop a Bayesian analysis to estimate the disease prevalence, the sensitivity and specificity of three cervical cancer screening tests (cervical cytology, visual inspection with acetic acid and Hybrid Capture II) in the presence of a covariate and in the absence of a gold standard. We use Metropolis-Hastings algorithm to obtain the posterior summaries of interest. The estimated prevalence of cervical lesions was 6.4% (a 95% credible interval [95% CI] was 3.9, 9.3). The sensitivity of cervical cytology (with a result of ≄ ASC-US) was 53.6% (95% CI: 42.1, 65.0) compared with 52.9% (95% CI: 43.5, 62.5) for visual inspection with acetic acid and 90.3% (95% CI: 76.2, 98.7) for Hybrid Capture II (with result of >1 relative light units). The specificity of cervical cytology was 97.0% (95% CI: 95.5, 98.4) and the specifi cities for visual inspection with acetic acid and Hybrid Capture II were 93.0% (95% CI: 91.0, 94.7) and 88.7% (95% CI: 85.9, 91.4), respectively. The Bayesian model with covariates suggests that the sensitivity and the specificity of the visual inspection with acetic acid tend to increase as the age of the women increases. The Bayesian method proposed here is an useful alternative to estimate measures of performance of diagnostic tests in the presence of covariates and when a gold standard is not available. An advantage of the method is the fact that the number of parameters to be estimated is not limited by the number of observations, as it happens with several frequentist approaches. However, it is important to point out that the Bayesian analysis requires informative priors in order for the parameters to be identifiable. The method can be easily extended for the analysis of other medical data sets.63346Begg, C.B., Greenes, R.A., Assessment of diagnostic tests when disease verification is subject to selection bias (1983) Biometrics, 39, pp. 207-215Zhou, X., Maximum likelihood estimators of sensitivity and specificity corrected for verification bias (1983) Commun Statis Theory Meth, 22, pp. 3177-3198Hui, S.L., Walter, S.D., Estimating the error rates of diagnostic tests (1980) Biometrics, 36, pp. 167-171Joseph, L., Gyorkos, T.W., Coupal, L., Bayesian estimation of disease prevalence and the parameters of diagnostic tests in the absence of a gold standard (1985) Am J Epidemiol, 141, pp. 263-272Hitt, E., Cancer in the Americas (2003) Lancet Oncol, 4, p. 9Brasil. MinistĂ©rio da SaĂșde. Secretaria Nacional de AssistĂȘncia Ă  SaĂșde. Instituto Nacional do CĂąncer. Estimativas da incidĂȘncia e mortalidade por cĂąncer no Brasil. Rio de Janeiro: INCA2002. Available on website: 〈http://www.inca.org.br/cancer/ epide miologia/estimativa2002/estimativas.html〉Mitchell, M.F., Schottenfeld, D., Tortolero-Luna, G., Cantor, S.B., Richards-Kortum R. Colposcopy for the diagnosis of squamous intraepithelial lesions: A meta-analysis (1998) Obstet Gynecol, 91, pp. 626-631Hopman, E.H., Kenemans, P., Helmerhorst, T.J., Positive predictive rate of colposcopic examination of the cervix uteri: An overview of literature (1998) Obstet Gynecol Surv, 53, pp. 97-106Begg, C.B., Biases in the assessment of diagnostic tests (1987) Stat Med, 6, pp. 411-423Hui, S.L., Zhou, X.H., Evaluation of diagnostic tests without gold standards (1998) Stat Methods Med Res, 7, pp. 354-370Zhou, X.H., Correcting for verification bias in studies of a diagnostic test's accuracy (1998) Stat Methods Med Res, 7, pp. 337-353McCrory, D.C., Matchar, D.B., Bastian, L. et al. 1999. Evaluation of cervical cytology. Evidence report/technology assessment n.5. (Prepared by Duke University under Contract n. 290-97-0014). AHCPR publication n. 99-E010. Rockville: Agency for Health Care Policy and ResearchDendukuri, N., Joseph, L., Bayesian approaches to modelling the conditional dependence between multiple diagnostic tests (2001) Biometrics, 57, pp. 208-217Faraone, S.V., Tsuang, M.T., Measuring diagnostic accuracy in the absence of a "gold standard (1994) Am J Psychiatry, 151, pp. 650-657Qu, Y., Tan, M., Kutner, M.H., Random effects models in latent class analysis for evaluating accuracy of diagnostic tests (1996) Biometrics, 52, pp. 797-810Hadgu, A., Qu, Y., A biomedical application of latent models with random effects (1998) Appl Statist, 47, pp. 603-616Tanner, M., Wong, W., The calculation of posterior distributions by data augmentation (1987) J Am Statist Ass, 82, pp. 528-550Gelfand, A.E., Smith, A.F.M., Sampling Based Approaches to Calculating Marginal Densities (1990) J Am Stat Assoc, 85, pp. 398-409Gelfand, A.E., Gibbs sampling (2000) J Am Stat Assoc, 95, pp. 1300-1304Syrjanen, K., Naud, P., Derchain, S., Comparing PAP smear cytology, aided visual inspection, screening colposcopy, cervicography and HPV testing as optional screening tools in Latin America. Study design and baseline data of the LAMS study (2005) Anticancer Res, 25, pp. 3469-3480Sarian, L.O., Derchain, S.F., Naud, P., Evaluation of visual inspection with acetic acid (VIA), Lugol's iodine (VILI), cervical cytology and HPV testing as cervical screening tools in Latin America. This report refers to partial results from the LAMS (Latin AMerican Screening) study (2005) J Med Screen, 12, pp. 142-149Solomon, D., Davey, D., Kurman, R., The 2001 Bethesda System: Terminology for reporting results of cervical cytology (2002) JAMA, 287, pp. 2114-2119Blumenthal, P., Sanghvi, H., (1997) Atlas for unaided visual inspection of the cervix, , Baltimore and Harare: JHPIEGO Corporation and University of Zimbabwe Medical SchoolNanda, K., McCrory, D.C., Myers, E.R., Accuracy of the Papanicolaou test in screening for and follow-up of cervical cytologic abnormalities: A systematic review (2000) Ann Intern Med, 132, pp. 810-819Belinson, J.L., Pretorius, R.G., Zhang, W.H., Wu, L.Y., Qiao, Y.L., Elson, P., Cervical cancer screening by simple visual inspection after acetic acid (2001) Obstet Gynecol, 98, pp. 441-444Visual inspection with acetic acid for cervical-cancer screening: Test qualities in a primary care setting (1999) Lancet, 353, pp. 869-873. , University of Zimbabwe/JHPIEGO Cervical Cancer ProjectSchiffman, M., Herrero, R., Hildensheim, A., HPV DNA testing in cervical cancer screening: Results from women in a high-risk province of Costa Rica (2000) JAMA, 283, pp. 87-93Wright Jr, T.C., Lynette, D., Kuhn, L., Pollack, A., Lorincz, A., HPV DNA testing of self-collected vaginal samples compared with cytologic screening to detect cervical cancer (2000) JAMA, 283, pp. 81-86Box, G.E.P., Tiao, G.C., (1992) Bayesian Inference in Statistical Analysis, , Reprint edition. New York: Wiley-InterscienceAltman, D.G., Bland, J.M., Diagnostic tests 2: Predictive values (1994) BMJ, 309, p. 102Franco, E.L., Primary screening of cervical cancer with human papillomavirus tests (2003) J Natl Cancer Inst Monogr, 31, pp. 89-96Geweke J. 1992. Evaluating the accuracy of sampling-based approaches to calculating posterior moments. Bayesian Statistics 4Bernardo, J.M.Berger, J.O.Dawid, A.P and.Smith, A.F.M., Eds.Clarendom Press: Oxford, 169-94Carlin, B.P., Louis, T.A., (2000) Bayes and empirical Bayes methods for data analysis, , 2nd ed. London: Chapman and Hall/CRCKoss, L.G., Human papillomavirus testing as a screening tool for cervical cancer (2000) JAMA, 283, p. 2525Shlay, J.C., Dunn, T., Byers, T., BarĂłn, A.E., Douglas, J.M., Prediction of cervical intraepithelial neoplasia grade 2-3 using risk assessment and human papillomavirus testing in women with atypia on Papanicolaou Smears (2000) Obstet Gynecol, 96, pp. 410-416Spiegelhalter, D.J., Best, N.G., Carlin, B.P., van der Linde A Bayesian measures of model complexity and fit (with discussion) (2002) J Roy Statist Soc B, 64, pp. 583-640Franco, E.L., Ferenczy, A., Assessing gains in diagnostic utility when human papillomavirus testing is used as an adjunct to papanicolaou smear in the triage of women with cervical cytologic abnormalities (1999) Am J Obstet Gynecol, 181, pp. 382-386Macaskill, P., Walter, S.D., Irwig, L., Franco, E.L., Assessing the gain in diagnostic performance when combining two diagnostic tests (2002) Statis Med, 21, pp. 2527-2546Brenner, H., How independent are multiple "independent" diagnostic classifications? Stat MedEspeland, M.A., Handelman, S.L., Using latent class models to characterize and assess relative error in discrete measurements (1989) Biometrics, 45, pp. 587-599Yang, I., Becker, M.P., Latent variable modeling of diagnostic accuracy (1997) Biometrics, 53, pp. 948-958Ratman, S., Franco, E.L., Ferenczy, A., Human papillomavirus testing for primary screening of cervical cancer precursors (2000) Cancer Epidemiol Biomarkers Prev, 9, pp. 945-951Coste, J., Cochand-Priollet, B., de Cremoux, P., Cross sectional study of conventional cervical smear, monolayer cytology and human papillomavirus DNA testing for cervical cancer screening (2003) BMJ, 326, p. 733Schiffman, M., Hildesheim, A., Herrero, R., Bratti, M., In reply: Human papillomavirus testing as a screening tool for cervical cancer (2000) JAMA, 283, pp. 2525-2526Londhe, M., George, S.S., Seshadri, L., Detection of CIN by naked eye visualization after application of acetic acid (1997) Indian J Cancer, 34, pp. 88-91Sankaranarayanan, R., Wesley, R., Somanathan, T., Visual inspection of the uterine cervix after the application of acetic acid in the detection of cervical carcinoma and its precursors (1998) Cancer, 83, pp. 2150-2156Sankaranarayanan, R., Shyamalayumary, B., Wesley, R., Sreedevi Amma, N., Parkin, D.M., Nair, M.K., Visual inspection with acetic acid in the early detection of cervical cancer and precursors (1999) Int J Cancer, 80, pp. 161-163Denny, L., Kuhn, L., Pollack, A., Wainwright, H., Wright Jr., T.C., Evaluation of alternative methods of cervical cancer screening in resource-poor settings (2000) Cancer, 89, pp. 826-833Denny, L., Kuhn, L., Pollack, A., Wright Jr., T.C., Direct visual inspection for cervical cancer screening: An analysis of factors influencing test performance (2002) Cancer, 94, pp. 1699-1707Parmigiani, G., Measuring uncertainty in complex decision analysis models (2002) Stat Methods Med Res, 11, pp. 513-537Koss, L.G., Human papillomavirus testing as a screening tool for cervical cancer (2000) JAMA, 283, pp. 2525-2526Smith, A.F.M., Roberts, G.O., Bayesian Computation via the Gibbs Sampler and Related MCMC Methods (1993) J R Stat SocB, 55, pp. 3-2

    NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

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    Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset

    Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

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    Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

    Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

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    We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

    Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

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    Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society

    Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

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    [no abstract available

    Open data from the third observing run of LIGO, Virgo, KAGRA, and GEO

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    The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

    Search for gravitational-wave transients associated with magnetar bursts in advanced LIGO and advanced Virgo data from the third observing run

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    Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant f lares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and longduration (∌100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA’s third observation run. These 13 bursts come from two magnetars, SGR1935 +2154 and SwiftJ1818.0−1607. We also include three other electromagnetic burst events detected by FermiGBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant flares were detected during the analysis period. We find no evidence of gravitational waves associated with any of these 16 bursts. We place upper limits on the rms of the integrated incident gravitational-wave strain that reach 3.6 × 10−ÂČÂł Hz at 100 Hz for the short-duration search and 1.1 ×10−ÂČÂČ Hz at 450 Hz for the long-duration search. For a ringdown signal at 1590 Hz targeted by the short-duration search the limit is set to 2.3 × 10−ÂČÂČ Hz. Using the estimated distance to each magnetar, we derive upper limits upper limits on the emitted gravitational-wave energy of 1.5 × 1044 erg (1.0 × 1044 erg) for SGR 1935+2154 and 9.4 × 10^43 erg (1.3 × 1044 erg) for Swift J1818.0−1607, for the short-duration (long-duration) search. Assuming isotropic emission of electromagnetic radiation of the burst ïŹ‚uences, we constrain the ratio of gravitational-wave energy to electromagnetic energy for bursts from SGR 1935+2154 with the available ïŹ‚uence information. The lowest of these ratios is 4.5 × 103

    A joint Fermi-GBM and Swift-BAT analysis of gravitational-wave candidates from the third gravitational-wave observing run

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    We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational-wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM onboard triggers and subthreshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift-BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma rays from binary black hole mergers
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