565 research outputs found
Apparatus for sensor failure detection and correction in a gas turbine engine control system
A gas turbine engine control system maintains a selected level of engine performance despite the failure or abnormal operation of one or more engine parameter sensors. The control system employs a continuously updated engine model which simulates engine performance and generates signals representing real time estimates of the engine parameter sensor signals. The estimate signals are transmitted to a control computational unit which utilizes them in lieu of the actual engine parameter sensor signals to control the operation of the engine. The estimate signals are also compared with the corresponding actual engine parameter sensor signals and the resulting difference signals are utilized to update the engine model. If a particular difference signal exceeds specific tolerance limits, the difference signal is inhibited from updating the model and a sensor failure indication is provided to the engine operator
Synthesis, radiolabelling and in vitro and in vivo evaluation of a novel fluorinated ABP688 derivative for the PET imaging of metabotropic glutamate receptor subtype 5
(E)-3-(Pyridin-2-ylethynyl)cyclohex-2-enone O-(2-(3-18F-fluoropropoxy)ethyl) oxime ([18F]-PSS223) was evaluated
in vitro and in vivo to establish its potential as a PET tracer for imaging metabotropic glutamate receptor subtype
5 (mGluR5). [18F]-PSS223 was obtained in 20% decay corrected radiochemical yield whereas the non-radioactive
PSS223 was accomplished in 70% chemical yield in a SN2 reaction of common intermediate mesylate 8 with potassium
fluoride. The in vitro binding affinity of [18F]-PSS223 was measured directly in a Scatchard assay to give Kd =
3.34 ± 2.05 nM. [18F]-PSS223 was stable in PBS and rat plasma but was significantly metabolized by rat liver microsomal
enzymes, but to a lesser extent by human liver microsomes. Within 60 min, 90% and 20% of [18F]-PSS223 was
metabolized by rat and human microsome enzymes, respectively. In vitro autoradiography on horizontal rat brain
slices showed heterogeneous distribution of [18F]-PSS223 with the highest accumulation in brain regions where
mGluR5 is highly expressed (hippocampus, striatum and cortex). Autoradiography in vitro under blockade conditions
with ABP688 confirmed the high specificity of [18F]-PSS223 for mGluR5. Under the same blocking conditions but using
the mGluR1 antagonist, JNJ16259685, no blockade was observed demonstrating the selectivity of [18F]-PSS223
for mGluR5 over mGluR1. Despite favourable in vitro properties of [18F]-PSS223, a clear-cut visualization of mGluR5-
rich brain regions in vivo in rats was not possible mainly due to a fast clearance from the brain and low metabolic
stability of [18F]-PSS223
Evolving Landscape of Carbapenem-Resistant
OBJECTIVES: The increased identification of carbapenem-resistant
METHODS: A total of 169 CR-PA isolated from clinical specimens at a single centre in Houston, TX, USA were studied. Among them, 61 isolates collected between 1999 and 2005 were defined as historical strains, and 108 collected between 2017 and 2018 were defined as contemporary strains. Antimicrobial susceptibilities against selected ÎČ-lactams was determined. WGS data were used for the identification of antimicrobial resistance determinants and phylogenetic analysis.
RESULTS: Non-susceptibility to ceftolozane/tazobactam and ceftazidime/avibactam increased from 2% (1/59) to 17% (18/108) and from 7% (4/59) to 17% (18/108) from the historical to the contemporary collection, respectively. Carbapenemase genes, which were not identified in the historical collection, were harboured by 4.6% (5/108) of the contemporary strains, and the prevalence of ESBL genes also increased from 3.3% (2/61) to 16% (17/108). Genes encoding acquired ÎČ-lactamases were largely confined to the high-risk clones. Among ceftolozane/tazobactam-resistant isolates, non-susceptibility to ceftazidime/avibactam, imipenem/relebactam and cefiderocol was observed in 94% (15/16), 56% (9/16) and 12.5% (2/16), respectively. Resistance to ceftolozane/tazobactam and imipenem/relebactam was primarily associated with the presence of exogenous ÎČ-lactamases.
CONCLUSIONS: Acquisition of exogenous carbapenemases and ESBLs may be a worrisome trend i
Recommended from our members
Submarine Basaltic Glass Colonization by the Heterotrophic Fe(II)-Oxidizing and Siderophore-Producing Deep-Sea Bacterium
Phylogenetically and metabolically diverse bacterial communities have been found in association with submarine basaltic glass surfaces. The driving forces behind basalt colonization are for the most part unknown. It remains ambiguous if basalt provides ecological advantages beyond representing a substrate for surface colonization, such as supplying nutrients and/or energy. Pseudomonas stutzeri VS-10, a metabolically versatile bacterium isolated from Vailulu'u Seamount, was used as a model organism to investigate the physiological responses observed when biofilms are established on basaltic glasses. In Fe-limited heterotrophic media, P. stutzeri VS-10 exhibited elevated growth in the presence of basaltic glass. Diffusion chamber experiments demonstrated that physical attachment or contact of soluble metabolites such as siderophores with the basaltic glass plays a pivotal role in this process. Electrochemical data indicated that P. stutzeri VS-10 is able to use solid substrates (electrodes) as terminal electron donors and acceptors. Siderophore production and heterotrophic Fe(II) oxidation are discussed as potential mechanisms enhancing growth of P. stutzeri VS-10 on glass surfaces. In correlation with that we discuss the possibility that metabolic versatility could represent a common and beneficial physiological trait in marine microbial communities being subject to oligotrophic and rapidly changing deep-sea conditions
Multifunctional shadeâtree management in tropical agroforestry landscapes â a review
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87099/1/j.1365-2664.2010.01939.x.pd
Recommended from our members
Wivesâ part-time employment and marital stability in Great Britain, West Germany and the United States
Many hail wivesâ part-time employment as a workâfamily balance strategy, but theories offer competing predictions as to the effects of wivesâ employment on relationship stability. We use panel data to test these competing hypotheses among recent cohorts of first-married couples in Great Britain, West Germany 1 and the United States. We find effects of wivesâ employment on marital stability var y across the countries. In West Germany with its high-quality part-time employment, couples where the wife works part time are significantly more stable. In the more liberal British and US labour markets, neither wivesâ part- nor full-time employment significantly alters divorce risk. In the United States, however, mothers working part time have significantly lower divorce risk. West German and British husbandsâ unemployment proves more detrimental to marital stability than wivesâ employment. These results highlight the importance of the socioeconomic context in structuring the optimal employment participation of both partners
Evaluation of Etest for Susceptibility Testing of Multidrug-Resistant Isolates of Mycobacterium tuberculosis
To prescribe effective treatment schemes for patients with tuberculosis, more-efficient susceptibility testing techniques for Mycobacterium tuberculosis are needed, especially in regions with multidrug resistance. Etest (AB BIODISK, Solna, Sweden) is a simple technique that provides quantitative drug susceptibility results for M. tuberculosis in 5 to 10 days from a culture grown at low cost. The performance of Etest was compared to that of the reference proportion method, using 95 M. tuberculosis clinical isolates of which 42.1% (40 of 95) were resistant to at least one antibiotic by the reference method. Overall agreement between Etest and the reference method was 98.9% (94 of 95) for detection of multidrug resistance; for resistance to individual drugs, agreement was 97.9% (93 of 95) for rifampin, 96.0% (92 of 95) for ethambutol, 94.7% (90 of 95) for isoniazid, and 85.3% (81 of 95) for streptomycin. This study supports the utility of Etest for timely detection of drug resistance in M. tuberculosis and for use in tuberculosis control programs
From Quantum Systems to L-Functions: Pair Correlation Statistics and Beyond
The discovery of connections between the distribution of energy levels of
heavy nuclei and spacings between prime numbers has been one of the most
surprising and fruitful observations in the twentieth century. The connection
between the two areas was first observed through Montgomery's work on the pair
correlation of zeros of the Riemann zeta function. As its generalizations and
consequences have motivated much of the following work, and to this day remains
one of the most important outstanding conjectures in the field, it occupies a
central role in our discussion below. We describe some of the many techniques
and results from the past sixty years, especially the important roles played by
numerical and experimental investigations, that led to the discovery of the
connections and progress towards understanding the behaviors. In our survey of
these two areas, we describe the common mathematics that explains the
remarkable universality. We conclude with some thoughts on what might lie ahead
in the pair correlation of zeros of the zeta function, and other similar
quantities.Comment: Version 1.1, 50 pages, 6 figures. To appear in "Open Problems in
Mathematics", Editors John Nash and Michael Th. Rassias. arXiv admin note:
text overlap with arXiv:0909.491
- âŠ