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Clinical Enterobacteriacae isolates with a colistin minimum inhibitory concentration (MIC) ≥4 mg/L from a United States hospital were screened for the mcr-1 gene using real-time polymerase chain reaction (RT-PCR) and confirmed by whole-genome sequencing. Four colistin-resistant Escherichia coli isolates contained mcr-1. Two isolates belonged to the same sequence type (ST-632). All subjects had prior international travel and antimicrobial exposure.
We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.
Hysteresis effect of barium strontium titanate (BST) thin films for gate dielectric application has been studied. It is found that the “counterclockwise” hysteresis has strong sweep voltage and operating temperature dependence. It can be reduced or eliminated by proper thermal annealing or by using a barrier layer. A charge trapping and detrapping mechanism has been proposed.
The kinetics of Ga incorporation during gas-source molecular beam epitaxy of GaN are investigated for varying substrate temperature and incident ammonia flux. Incident Ga atoms eventually either: 1) react with NH3 to form GaN, 2) accumulate on the film surface, or 3) desorb. Low substrate temperatures lead to significant Ga surface accumulation due to the temperature-dependent reactivity of NH3 towards Ga. High substrate temperatures give rise to significant Ga desorption. Increasing NH3 flux retards both Ga surface accumulation and Ga desorption. The GaN formation rate variation with substrate temperature peaks near 750°C and increases with NH3 flux. The observation of two distinct and very low activation energies for Ga desorption suggests a relatively complex surface chemistry and a strong likelihood that hydrogen is playing an important role.