Evaluation of the SAMEO-ATO surgical classification in a Dutch cohort

Purpose: Differences in the definition and classification of cholesteatoma hinders comparing of surgical outcomes of cholesteatoma. Uniform registration is necessary to allow investigators to share and compare their findings. For many years surgical cholesteatoma procedures were divided into two main groups: canal wall up mastoidectomy (CWU) and canal wall down mastoidectomy (CWD). Recently, mastoid obliteration can be added to both procedures. Because of great variation within these main groups, the International Otology Outcome Group (IOOG) proposed the new SAMEO-ATO classification system to categorize tympanomastoid operations. The aim of our study was to correlate the mastoid bone extirpation (M-stage) with the contemporary (CWU, CWD with or without obliteration) system. Methods: Demographic characteristics and type of performed surgery were registered for 135 cholesteatoma patients from sixteen hospitals, both secondary and tertiary care institutions, across the Netherlands. In addition, the surgical reports were collected, retrospectively classified according to the contemporary system and the new system and compared. Correlations of the outcomes were calculated. Results: In total, there were 112 CWU and 14 CWD (both with or without obliteration) suitable for correlation analysis. Z test for correlation between the M-stage and CWU procedure was significant for M1a and M1b procedure and significant for M2c with the CWD procedure. Conclusion: The newly proposed SAMEO-ATO classification seems to be more detailed in the registration of surgical procedures than surgeons currently are used to. All M-stages of the SAMEO-ATO system are correlating well to the standard CWU and CWD except one ‘in between’ M-stage

Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO’s fifth science run. At low frequencies, 40–460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460–1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of Ω(f) < 7.7 × 10[superscript -4](f/900  Hz)[superscript 3], which improves on the previous upper limit by a factor of ~180. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.National Science Foundation (U.S.)United States. National Aeronautics and Space AdministrationCarnegie TrustDavid & Lucile Packard FoundationAlfred P. Sloan Foundatio

Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO’s fifth science run. At low frequencies, 40–460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460–1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of Ω(f)<7.7×10−4(f/900  Hz)3, which improves on the previous upper limit by a factor of ∼180. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors