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

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

Practical application of the Delphi technique in a bicultural mental health nursing study in New Zealand

Background. Numerous studies have employed the Delphi technique to seek expert opinion about aspects of clinical practice. When researching literature on the Delphi technique, however, we discovered discrepancies in its application, and a lack of detail when reporting design, administration, and analysis methods. Such lack of specificity hinders the replicability and assessment of the clinical and cultural validity and reliability of Delphi studies.Aim. The aim of this paper is to detail the practical application of the Delphi technique as a culturally and clinically valid means of accessing expert opinion on the importance of clinical criteria.Methods. Reference is made to a bicultural New Zealand mental health nursing clinical indicator study that employed a three-round reactive Delphi survey. Equal proportions of Maori and non-Maori nurses (n = 20) and consumers (n = 10) rated the importance of 91 clinical indicator statements for the achievement of professional practice standards. Additional statements (n = 21) suggested by Delphi participants in round 1 were included in subsequent rounds. In round 2, participants explained the rating they applied to statements that had not reached consensus in round 1, and summarized responses were provided to participants in round 3. Consensus was considered to have been achieved if 85% of round 3 ratings lay within a 2-point bracket on the 5-point Likert-scale overall, or in one of the Maori nurse, non-Maori nurse, or consumer groups. A mean rating of 4&middot;5 after round 3 was set as the importance threshold.Findings. Consensus occurred overall on 75 statements, and within groups on another 24. Most statements (n = 86) reached the importance benchmark.Conclusions. When rigorous methods of participant selection, group composition, participant feedback, and determination of consensus and importance are employed, the Delphi technique is a reliable, cost-effective means of obtaining and prioritizing experts judgements.<br /

Broadband quantum enhancement of the LIGO detectors with frequency-dependent squeezing

Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. Here, we present the first realization of frequency-dependent squeezing in full-scale gravitational-wave detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, with broadband detector enhancement from tens of hertz to several kilohertz. In the LIGO Hanford detector, squeezing reduced the detector noise amplitude by a factor of 1.6 (4.0 dB) near 1 kHz; in the Livingston detector, the noise reduction was a factor of 1.9 (5.8 dB). These improvements directly impact LIGO’s scientific output for high-frequency sources (e.g., binary neutron star postmerger physics). The improved low-frequency sensitivity, which boosted the detector range by 15%–18% with respect to no squeezing, corresponds to an increase in the astrophysical detection rate of up to 65%. Frequency-dependent squeezing was enabled by the addition of a 300-meter-long filter cavity to each detector as part of the LIGO A + upgrade