9 research outputs found

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

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    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 102210^{-22}.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200

    Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers

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    We study frequency dependent (FD) input-output schemes for signal-recycling interferometers, the baseline design of Advanced LIGO and the current configuration of GEO 600. Complementary to a recent proposal by Harms et al. to use FD input squeezing and ordinary homodyne detection, we explore a scheme which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are sub-optimal among all possible input-output schemes, provide a global noise suppression by the power squeeze factor, while being realizable by using detuned Fabry-Perot cavities as input/output filters. At high frequencies, the two schemes are shown to be equivalent, while at low frequencies our scheme gives better performance than that of Harms et al., and is nearly fully optimal. We then study the sensitivity improvement achievable by these schemes in Advanced LIGO era (with 30-m filter cavities and current estimates of filter-mirror losses and thermal noise), for neutron star binary inspirals, and for narrowband GW sources such as low-mass X-ray binaries and known radio pulsars. Optical losses are shown to be a major obstacle for the actual implementation of these techniques in Advanced LIGO. On time scales of third-generation interferometers, like EURO/LIGO-III (~2012), with kilometer-scale filter cavities, a signal-recycling interferometer with the FD readout scheme explored in this paper can have performances comparable to existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi

    Efferent limb stimulation prior to loop ileostomy closure: a systematic review and meta-analysis

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    Background: Postoperative ileus (POI) remains a common phenomenon following loop ileostomy closure. Our aim was to determine whether preoperative physiological stimulation (PPS) of the efferent limb reduced POI incidence. Methods: A PRISMA-compliant meta-analysis searching PubMed, EMBASE and CENTRAL databases was performed. The last search was carried out on 30 January 2023. All randomized studies comparing PPS versus no stimulation were included. The primary endpoint was POI incidence. Secondary endpoints included the time to first passage of flatus/stool, time to resume oral diet, need for nasogastric tube (NGT) placement postoperatively, length of stay (LOS) and other complications. Random effects models were used to calculate pooled effect size estimates. Trial sequential analyses (TSA) were also performed. Results: Three randomized studies capturing 235 patients (116 PPS, 119 no stimulation) were included. On random effects analysis, PPS was associated with a quicker time to resume oral diet (MD - 1.47 days, 95% CI - 2.75 to - 0.19, p = 0.02), shorter LOS (MD - 1.47 days, 95% CI - 2.47 to - 0.46, p = 0.004) (MD - 1.41 days, 95% CI - 2.32 to - 0.50, p = 0.002, I2 = 56%) and fewer other complications (OR 0.42, 95% CI 0.18 to 1.01, p = 0.05). However, there was no difference in POI incidence (OR 0.35, 95% CI 0.10 to 1.21, p = 0.10), the requirement for NGT placement (OR 0.50, 95% CI 0.21 to 1.20, p = 0.12) or time to first passage of flatus/stool (MD - 0.60 days, 95% CI - 1.95 to 0.76, p = 0.39). TSA revealed imprecise estimates for all outcomes (except LOS) and further studies are warranted to meet the required information threshold. Conclusions: PPS prior to stoma closure may reduce LOS and postoperative complications albeit without a demonstrable beneficial effect on POI. Further high-powered studies are required to confirm or refute these findings.</p

    Efferent limb stimulation prior to loop ileostomy closure: a systematic review and meta-analysis

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    Background: Postoperative ileus (POI) remains a common phenomenon following loop ileostomy closure. Our aim was to determine whether preoperative physiological stimulation (PPS) of the efferent limb reduced POI incidence. Methods: A PRISMA-compliant meta-analysis searching PubMed, EMBASE and CENTRAL databases was performed. The last search was carried out on 30 January 2023. All randomized studies comparing PPS versus no stimulation were included. The primary endpoint was POI incidence. Secondary endpoints included the time to first passage of flatus/stool, time to resume oral diet, need for nasogastric tube (NGT) placement postoperatively, length of stay (LOS) and other complications. Random effects models were used to calculate pooled effect size estimates. Trial sequential analyses (TSA) were also performed. Results: Three randomized studies capturing 235 patients (116 PPS, 119 no stimulation) were included. On random effects analysis, PPS was associated with a quicker time to resume oral diet (MD - 1.47 days, 95% CI - 2.75 to - 0.19, p = 0.02), shorter LOS (MD - 1.47 days, 95% CI - 2.47 to - 0.46, p = 0.004) (MD - 1.41 days, 95% CI - 2.32 to - 0.50, p = 0.002, I2 = 56%) and fewer other complications (OR 0.42, 95% CI 0.18 to 1.01, p = 0.05). However, there was no difference in POI incidence (OR 0.35, 95% CI 0.10 to 1.21, p = 0.10), the requirement for NGT placement (OR 0.50, 95% CI 0.21 to 1.20, p = 0.12) or time to first passage of flatus/stool (MD - 0.60 days, 95% CI - 1.95 to 0.76, p = 0.39). TSA revealed imprecise estimates for all outcomes (except LOS) and further studies are warranted to meet the required information threshold. Conclusions: PPS prior to stoma closure may reduce LOS and postoperative complications albeit without a demonstrable beneficial effect on POI. Further high-powered studies are required to confirm or refute these findings.</p

    LIGO: S1 Science Results and Plans Beyond

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    Global Incidence and Risk Factors Associated With Postoperative Urinary Retention Following Elective Inguinal Hernia Repair

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    Importance Postoperative urinary retention (POUR) is a well-recognized complication of inguinal hernia repair (IHR). A variable incidence of POUR has previously been reported in this context, and contradictory evidence surrounds potential risk factors.Objective To ascertain the incidence of, explore risk factors for, and determine the health service outcomes of POUR following elective IHR.Design, Setting, and Participants The Retention of Urine After Inguinal Hernia Elective Repair (RETAINER I) study, an international, prospective cohort study, recruited participants between March 1 and October 31, 2021. This study was conducted across 209 centers in 32 countries in a consecutive sample of adult patients undergoing elective IHR.Exposure Open or minimally invasive IHR by any surgical technique, under local, neuraxial regional, or general anesthesia.Main Outcomes and Measures The primary outcome was the incidence of POUR following elective IHR. Secondary outcomes were perioperative risk factors, management, clinical consequences, and health service outcomes of POUR. A preoperative International Prostate Symptom Score was measured in male patients.Results In total, 4151 patients (3882 male and 269 female; median [IQR] age, 56 [43-68] years) were studied. Inguinal hernia repair was commenced via an open surgical approach in 82.2% of patients (n = 3414) and minimally invasive surgery in 17.8% (n = 737). The primary form of anesthesia was general in 40.9% of patients (n = 1696), neuraxial regional in 45.8% (n = 1902), and local in 10.7% (n = 446). Postoperative urinary retention occurred in 5.8% of male patients (n = 224), 2.97% of female patients (n = 8), and 9.5% (119 of 1252) of male patients aged 65 years or older. Risk factors for POUR after adjusted analyses included increasing age, anticholinergic medication, history of urinary retention, constipation, out-of-hours surgery, involvement of urinary bladder within the hernia, temporary intraoperative urethral catheterization, and increasing operative duration. Postoperative urinary retention was the primary reason for 27.8% of unplanned day-case surgery admissions (n = 74) and 51.8% of 30-day readmissions (n = 72).Conclusions The findings of this cohort study suggest that 1 in 17 male patients, 1 in 11 male patients aged 65 years or older, and 1 in 34 female patients may develop POUR following IHR. These findings could inform preoperative patient counseling. In addition, awareness of modifiable risk factors may help to identify patients at increased risk of POUR who may benefit from perioperative risk mitigation strategies

    Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study

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