Analysis of LIGO data for gravitational waves from binary neutron stars

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of [Formula Presented] per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range [Formula Presented] © 2004 The American Physical Society

Analysis of first LIGO science data for stochastic gravitational waves

We present the analysis of between 50 and 100 h of coincident interferometric strain data used to search for and establish an upper limit on a stochastic background of gravitational radiation. These data come from the first LIGO science run, during which all three LIGO interferometers were operated over a 2-week period spanning August and September of 2002. The method of cross correlating the outputs of two interferometers is used for analysis. We describe in detail practical signal processing issues that arise when working with real data, and we establish an observational upper limit on a [Formula Presented] power spectrum of gravitational waves. Our 90% confidence limit is [Formula Presented] in the frequency band 40–314 Hz, where [Formula Presented] is the Hubble constant in units of 100 km/sec/Mpc and [Formula Presented] is the gravitational wave energy density per logarithmic frequency interval in units of the closure density. This limit is approximately [Formula Presented] times better than the previous, broadband direct limit using interferometric detectors, and nearly 3 times better than the best narrow-band bar detector limit. As LIGO and other worldwide detectors improve in sensitivity and attain their design goals, the analysis procedures described here should lead to stochastic background sensitivity levels of astrophysical interest. © 2004 The American Physical Society

First upper limits from LIGO on gravitational wave bursts

We report on a search for gravitational wave bursts using data from the first science run of the Laser Interferometer Gravitational Wave Observatory (LIGO) detectors. Our search focuses on bursts with durations ranging from 4 to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at a 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine Gaussians) as a function of their root-sum-square strain [Formula Presented] typical sensitivities lie in the range [Formula Presented] depending on the waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors. © 2004 The American Physical Society

Setting upper limits on the strength of periodic gravitational waves from PSR [Formula Presented] using the first science data from the GEO 600 and LIGO detectors

Data collected by the GEO 600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar [Formula Presented] at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: Frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar’s gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar’s equatorial ellipticity. © 2004 The American Physical Society

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times 10-22

Detector description and performance for the first coincidence observations between LIGO and GEO

For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data. © 2003 Elsevier B.V. All rights reserved

The role of the supply chain in the elimination and reduction of construction rework and defects: an action research approach

Since 2007, Ireland has suffered a circa 80% reduction in construction output. This has resulted in bankruptcy, unemployment and bad debt. Contractors have attached greater emphasis to production efficiency and cost reduction as a means of survival. An Action Research (AR) strategy was used in this research to improve processes adopted by a SME contractor for the control of defects in its supply chain. It is conservatively estimated that rework, typically accounts for, circa 5% of total project costs. Rework is wasteful and presents an obvious target for improvement. The research reported here concerns the (first) diagnosing stage of the AR cycle only, involving: observation of fieldwork, analysis of contract documents, and semi-structured interviews with supply chain members. The results indicate potential for supply chain participants to identify root causes of defects and propose solutions, having regard to best practice to avoid re-occurrence. A lack of collaborative forums to contribute to production improvement was identified. Additionally the processes, used to collect, manage and disseminate data were unstructured and uncoordinated, indicating scope for developing more efficient methods. The research indicates good understanding of the potential benefits for supply chain collaboration but suggests that the tools and knowledge to collaborate are currently lacking in the SME sector

Staff and patient experiences of decision-making about continuous observation in psychiatric hospitals

Purpose: Continuous observation of psychiatric inpatients aims to protect those who pose an acute risk of harm to self or others, but involves intrusive privacy restrictions. Initiating, conducting and ending continuous observation requires complex decision-making about keeping patients safe whilst protecting their privacy. There is little published guidance about how to balance privacy and safety concerns, and how staff and patients negotiate this in practice is unknown. To inform best practice, the present study, therefore, aimed to understand how staff and patients experience negotiating the balance between privacy and safety during decision-making about continuous observation. Methods: Thematic analysis of qualitative interviews with thirty-one inpatient psychiatric staff and twenty-eight inpatients. Results: Most patients struggled with the lack of privacy but valued feeling safe during continuous observation. Staff and patients linked good decision-making to using continuous observation for short periods and taking positive risks, understanding and collaborating with the patient, and working together as a supportive staff team. Poor decision-making was linked to insufficient consideration of observation’s iatrogenic potential, insufficient collaboration with patients, and the stressful impact on staff of conducting observations and managing risk. Conclusions: Best practice in decision-making about continuous observation may be facilitated by making decisions in collaboration with patients, and by staff supporting each-other in positive risk-taking. To achieve truly patient-centred decision-making, decisions about observation should not be influenced by staff’s own stress levels. To address the negative impact of staff stress on decision-making, it may be helpful to improve staff training, education and support structures

First upper limits from LIGO on gravitational wave bursts

We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.Comment: 21 pages, 15 figures, accepted by Phys Rev D. Fixed a few small typos and updated a few reference