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- de Graauw, Th., et al.
(författare)
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The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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- Lalani, Tahaniyat, et al.
(författare)
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Analysis of the impact of early surgery on in-hospital mortality of native valve endocarditis: use of propensity score and instrumental variable methods to adjust for treatment-selection bias.
- 2010
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Ingår i: Circulation. - 1524-4539. ; 121:8, s. 1005-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The impact of early surgery on mortality in patients with native valve endocarditis (NVE) is unresolved. This study sought to evaluate valve surgery compared with medical therapy for NVE and to identify characteristics of patients who are most likely to benefit from early surgery. METHODS AND RESULTS: Using a prospective, multinational cohort of patients with definite NVE, the effect of early surgery on in-hospital mortality was assessed by propensity-based matching adjustment for survivor bias and by instrumental variable analysis. Patients were stratified by propensity quintile, paravalvular complications, valve perforation, systemic embolization, stroke, Staphylococcus aureus infection, and congestive heart failure. Of the 1552 patients with NVE, 720 (46%) underwent early surgery and 832 (54%) were treated with medical therapy. Compared with medical therapy, early surgery was associated with a significant reduction in mortality in the overall cohort (12.1% [87/720] versus 20.7% [172/832]) and after propensity-based matching and adjustment for survivor bias (absolute risk reduction [ARR] -5.9%, P<0.001). With a combined instrument, the instrumental-variable-adjusted ARR in mortality associated with early surgery was -11.2% (P<0.001). In subgroup analysis, surgery was found to confer a survival benefit compared with medical therapy among patients with a higher propensity for surgery (ARR -10.9% for quintiles 4 and 5, P=0.002) and those with paravalvular complications (ARR -17.3%, P<0.001), systemic embolization (ARR -12.9%, P=0.002), S aureus NVE (ARR -20.1%, P<0.001), and stroke (ARR -13%, P=0.02) but not those with valve perforation or congestive heart failure. CONCLUSIONS: Early surgery for NVE is associated with an in-hospital mortality benefit compared with medical therapy alone.
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- Wang, Andrew, et al.
(författare)
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Contemporary clinical profile and outcome of prosthetic valve endocarditis.
- 2007
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Ingår i: JAMA : the journal of the American Medical Association. - : American Medical Association (AMA). - 1538-3598. ; 297:12, s. 1354-61
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Prosthetic valve endocarditis (PVE) is associated with significant mortality and morbidity. The contemporary clinical profile and outcome of PVE are not well defined. OBJECTIVES: To describe the prevalence, clinical characteristics, and outcome of PVE, with attention to health care-associated infection, and to determine prognostic factors associated with in-hospital mortality. DESIGN, SETTING, AND PARTICIPANTS: Prospective, observational cohort study conducted at 61 medical centers in 28 countries, including 556 patients with definite PVE as defined by Duke University diagnostic criteria who were enrolled in the International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to August 2005. MAIN OUTCOME MEASURE: In-hospital mortality. RESULTS: Definite PVE was present in 556 (20.1%) of 2670 patients with infective endocarditis. Staphylococcus aureus was the most common causative organism (128 patients [23.0%]), followed by coagulase-negative staphylococci (94 patients [16.9%]). Health care-associated PVE was present in 203 (36.5%) of the overall cohort. Seventy-one percent of health care-associated PVE occurred within the first year of valve implantation, and the majority of cases were diagnosed after the early (60-day) period. Surgery was performed in 272 (48.9%) patients during the index hospitalization. In-hospital death occurred in 127 (22.8%) patients and was predicted by older age, health care-associated infection (62/203 [30.5%]; adjusted odds ratio [OR], 1.62; 95% confidence interval [CI], 1.08-2.44; P = .02), S aureus infection (44/128 [34.4%]; adjusted OR, 1.73; 95% CI, 1.01-2.95; P = .05), and complications of PVE, including heart failure (60/183 [32.8%]; adjusted OR, 2.33; 95% CI, 1.62-3.34; P<.001), stroke (34/101 [33.7%]; adjusted OR, 2.25; 95% CI, 1.25-4.03; P = .007), intracardiac abscess (47/144 [32.6%]; adjusted OR, 1.86; 95% CI, 1.10-3.15; P = .02), and persistent bacteremia (27/49 [55.1%]; adjusted OR, 4.29; 95% CI, 1.99-9.22; P<.001). CONCLUSIONS: Prosthetic valve endocarditis accounts for a high percentage of all cases of infective endocarditis in many regions of the world. Staphylococcus aureus is now the leading cause of PVE. Health care-associated infection significantly influences the clinical characteristics and outcome of PVE. Complications of PVE strongly predict in-hospital mortality, which remains high despite prompt diagnosis and the frequent use of surgical intervention.
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