13,461 research outputs found
Risk factors for failure of outpatient parenteral antibiotic therapy (OPAT) in infective endocarditis
Objectives:
To identify risk factors for failure of outpatient antibiotic therapy (OPAT) in infective endocarditis (IE).
Patients and methods:
We identified IE cases managed at a single centre over 12 years from a prospectively maintained database. âOPAT failureâ was defined as unplanned readmission or antibiotic switch due to adverse drug reaction or antibiotic resistance. We analysed patient and disease-related risk factors for OPAT failure by univariate and multivariate logistic regression. We also retrospectively collected follow-up data on adverse disease outcome (defined as IE-related death or relapse) and performed KaplanâMeier survival analysis up to 36 months following OPAT.
Results:
We identified 80 episodes of OPAT in IE. Failure occurred in 25/80 episodes (31.3%). On multivariate analysis, cardiac or renal failure [pooled OR 7.39 (95% CI 1.84â29.66), Pâ=â0.005] and teicoplanin therapy [OR 8.69 (95% CI 2.01â37.47), Pâ=â0.004] were independently associated with increased OPAT failure. OPAT failure with teicoplanin occurred despite therapeutic plasma levels. OPAT failure predicted adverse disease outcome up to 36 months (Pâ=â0.016 log-rank test).
Conclusions:
These data caution against selecting patients with endocarditis for OPAT in the presence of cardiac or renal failure and suggest teicoplanin therapy may be associated with suboptimal OPAT outcomes. Alternative regimens to teicoplanin in the OPAT setting should be further investigated
A three-dimensional finite-element thermal/mechanical analytical technique for high-performance traveling wave tubes
Current research in high-efficiency, high-performance traveling wave tubes (TWT's) has led to the development of novel thermal/ mechanical computer models for use with helical slow-wave structures. A three-dimensional, finite element computer model and analytical technique used to study the structural integrity and thermal operation of a high-efficiency, diamond-rod, K-band TWT designed for use in advanced space communications systems. This analysis focused on the slow-wave circuit in the radiofrequency section of the TWT, where an inherent localized heating problem existed and where failures were observed during earlier cold compression, or 'coining' fabrication technique that shows great potential for future TWT development efforts. For this analysis, a three-dimensional, finite element model was used along with MARC, a commercially available finite element code, to simulate the fabrication of a diamond-rod TWT. This analysis was conducted by using component and material specifications consistent with actual TWT fabrication and was verified against empirical data. The analysis is nonlinear owing to material plasticity introduced by the forming process and also to geometric nonlinearities presented by the component assembly configuration. The computer model was developed by using the high efficiency, K-band TWT design but is general enough to permit similar analyses to be performed on a wide variety of TWT designs and styles. The results of the TWT operating condition and structural failure mode analysis, as well as a comparison of analytical results to test data are presented
Anisotropic Distribution of SDSS Satellite Galaxies: Planar (not Polar) Alignment
The distribution of satellite galaxies relative to isolated host galaxies in
the Sloan Digital Sky Survey (SDSS) is investigated. Host-satellite systems are
selected using three different methods, yielding samples of ~3300, ~1600, and
\~950 satellites. In the plane of the sky, the distributions of all three
samples show highly significant deviations from circular symmetry (> 99.99%, >
99.99%, and 99.79% confidence levels, respectively), and the degree of
anisotropy is a strong function of the projected radius, r_p, at which the
satellites are found. For r_p < 100 kpc, the SDSS satellites are aligned
preferentially with the major axes of the hosts. This is in stark contrast to
the Holmberg effect, in which satellites are aligned with the minor axes of
host galaxies. The degree of anisotropy in the distribution of the SDSS
satellites decreases with r_p and is consistent with an isotropic distribution
at of order the 1-sigma level for 250 kpc < r_p < 500 kpc.Comment: ApJ Letters (in press); Discussion section substantially revised,
SDSS DR3 included in the analysis, no significant changes to the result
Recommended from our members
The Relative Importance of Different Trophic Pathways for Secondary Exposure to Anticoagulant Rodenticides
Secondary exposure of predators to anticoagulant rodenticides, and in particular second generation anticoagulant rodenticides (SGARs), is a global phenomenon. The widespread and large-scale nature of this exposure has attracted considerable concern, although the consequences in terms of likelihood of poisoning of individuals and resultant impacts on populations are not well characterised. Secondary exposure of predators may as rise from once or more of: (i) eating contaminated commensal rodents subject to control (target species are typically rats and house mice); (ii) consumption of contaminated non-target small mammals (such as Peromyscus, Microtus, and Apodemus species) that encounter and feed on what are rodent-attractive baits; (iii) consumption of non-rodent vertebrate and invertebrate prey that may also incidentally encounter and eat baits. We hypothesised that predators feeding primarily on target species may be most at risk of exposure to SGARs while those predominantly taking non-mammalian prey may be at least risk. We tested this hypothesis by comparing exposure, determined from the presence and magnitude of SGAR liver residues, in red kites (Milvus milvus), which feeds extensively on rats, in barn owls (Tyto alba), kestrels (Falco tinnunculus), and tawny owls (Strix aluco) that feed widely on non-target small mammals, and in sparrowhawks (Accipiter nisus) that feed predominantly on small birds. We found that the scale and magnitude of exposure was broadly consistent with our hypothesis, and that controlling for age in the analysis could be important as older birds can accumulate residues with age. However, exposure in kestrels was typically greater than that in barn owls and tawny owls, despite what is thought to be a general similarity among the species in their diets. We discuss the relative importance of trophic pathways relative to other factors that may drive secondary exposure in predators, and confirm that species that feed on rats or other target species may be at most risk of exposure and poisoning
Characteristics and capacities of the NASA Lewis Research Center high precision 6.7- by 6.7-m planar near-field scanner
A very precise 6.7- by 6.7-m planar near-field scanner has recently become operational at the NASA Lewis Research Center. The scanner acquires amplitude and phase data at discrete points over a vertical rectangular grid. During the design phase for this scanner, special emphasis was given to the dimensional stability of the structures and the ease of adjustment of the rails that determine the accuracy of the scan plane. A laser measurement system is used for rail alignment and probe positioning. This has resulted in very repeatable horizontal and vertical motion of the probe cart and hence precise positioning in the plane described by the probe tip. The resulting accuracy will support near-field measurements at 60 GHz without corrections. Subsystem design including laser, electronic and mechanical and their performance is described. Summary data are presented on the scan plane flatness and environmental temperature stability. Representative near-field data and calculated far-field test results are presented. Prospective scanner improvements to increase test capability are also discussed
Wildlife Biologist, Division of Migratory Bird Management, U.S. Fish and Wildlife Service, Denver, Colorado
The abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2004, uncorrected for visibility bias, was 356,850. The photo-corrected 3-year average for 2001-2003 was 370,300, which is within the established population objective range of 343,000-465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2003- 04. About 7,700 hunters participated in these seasons, which was similar to the number that participated in the previous yearâs seasons. Hunters harvested 18,527 in the Central Flyway during the 2003-04 seasons, which was 42% higher than the harvest for the previous year. The retrieved harvest in the Pacific Flyway, Canada, and Mexico combined was estimated at 13,109 during 2003-04. The preliminary estimate for the North American sport harvest, including crippling losses, was 35,706, which is 28% higher than the previous yearâs estimate of 27,839 and the second highest harvest recorded. The long-term (1982-2000) trends for the Mid- Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2003 pre-migration survey estimate for the Rocky Mountain Population was 19,523, which was similar to the previous yearâs estimate of 18,803. The 3-year average for 2001-2003 is 18,295, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2003-04 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 528 cranes, a 17% decrease from the harvest of 639 the year before
Status and Harvests of Sandhill Cranes: Mid-Continent & Rocky Mountain Populations 2005
Annual indices to abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2005, uncorrected for visibility bias, was 412,000. The photo-corrected 3-year average for 2002-2004 was 363,167, which is within the established population-objective range of 343,000- 465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2004-05. About 9,300 hunters participated in these seasons, which was 12% higher than the number that participated in the previous yearâs seasons. Hunters harvested 15,124 cranes in the U.S. portion of the Central Flyway during the 2004-05 seasons, which was 18% lower than the estimated harvest for the previous year. The retrieved harvest of Mid-Continent Population sandhill cranes in hunt areas for the Rocky Mountain Population of sandhill cranes (Arizona & New Mexico), Alaska, Canada, and Mexico combined was estimated at 14,528 during 2004-05. The preliminary estimate for the North American sport harvest, including crippling losses, was 33,847, which is 5% lower than the previous yearâs estimate of 35,671. The long-term (1982-2004) trends for the Mid-Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2004 pre-migration survey estimate for the Rocky Mountain Population was 18,510, which was 5.5% lower than the previous yearâs estimate of 19,523. The 3-year average for 2002-2004 is 18,945, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2004-05 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 594 cranes, a 13% increase from the harvest of 528 the year before
Exploring the Literacy Leadership Practices of Literacy Teacher Educators
Literacy teacher educators must actively engage as literacy leaders who are advocates for literacy, continuous professional learners, and responsive leaders. However, the literature base for literacy leadership is narrow and does not specifically address literacy teacher educators. To address this research gap, the current study explored current literacy leadership practices of literacy teacher educators and challenges they encounter during their literacy leadership pursuits. Using a survey research design, quantitative and qualitative data were collected among 65 experienced literacy teacher educators affiliated with university-based teacher preparation programs located in the South Central United States. Quantitative data were tabulated and reported as frequencies, and qualitative data were analyzed using three levels of coding. Findings revealed preliminary understandings about the literacy leadership practices of literacy teacher educators and pointed to three practical implications for teacher preparation programs administrators and leaders of professional organizations
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