Scanning electrochemical cell microscopy : a versatile technique for nanoscale electrochemistry and functional imaging

Scanning electrochemical cell microscopy (SECCM) is a new pipette-based imaging technique purposely designed to allow simultaneous electrochemical, conductance, and topographical visualization of surfaces and interfaces. SECCM uses a tiny meniscus or droplet, confined between the probe and the surface, for high-resolution functional imaging and nanoscale electrochemical measurements. Here we introduce this technique and provide an overview of its principles, instrumentation, and theory. We discuss the power of SECCM in resolving complex structure-activity problems and provide considerable new information on electrode processes by referring to key example systems, including graphene, graphite, carbon nanotubes, nanoparticles, and conducting diamond. The many longstanding questions that SECCM has been able to answer during its short existence demonstrate its potential to become a major technique in electrochemistry and interfacial science

The impact of vancomycin susceptibility on treatment outcomes among patients with methicillin resistant Staphylococcus aureus bacteremia

<p>Abstract</p> <p>Background</p> <p>Management of methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) bacteremia remains a challenge. The emergence of MRSA strains with reduced vancomycin susceptibility complicates treatment.</p> <p>Methods</p> <p>A prospective cohort study (2005-2007) of patients with MRSA bacteremia treated with vancomycin was performed at an academic hospital. Vancomycin minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for stored MRSA isolates. Cox regression analysis was performed to predict 28-day all-cause mortality.</p> <p>Results</p> <p>One hundred sixty-three patients with MRSA bacteremia were evaluated. One hundred twelve patients (68.7%) had bacteremia due to MRSA with a vancomycin MIC ≥ 2 <it>ug</it>/mL. Among strains with a vancomycin MIC ≥ 2 <it>ug</it>/mL, 10 isolates (8.9%) were vancomycin-intermediate <it>S. aureus </it>(VISA). Thirty-five patients (21.5%) died within 28 days after the diagnosis of MRSA bacteremia. Higher vancomycin MIC was not associated with mortality in this cohort [adjusted hazard ratio (aHR), 1.57; 95% confidence interval (CI), 0.73-3.37]. Vancomycin tolerance was observed in 4.3% (7/162) of isolates and was not associated with mortality (crude HR, 0.62; 95% CI, 0.08-4.50). Factors independently associated with mortality included higher age (aHR, 1.03; 95% CI 1.00-1.05), cirrhosis (aHR, 3.01; 95% CI, 1.24-7.30), and intensive care unit admission within 48 hours after the diagnosis of bacteremia (aHR, 5.99; 95% CI, 2.86-12.58).</p> <p>Conclusions</p> <p>Among patients with MRSA bacteremia treated with vancomycin, reduced vancomycin susceptibility and vancomycin tolerance were not associated with mortality after adjusting for patient factors. Patient factors including severity of illness and underlying co-morbidities were associated with the mortality.</p

The Nature and Frequency of the Gas Outbursts in Comet 67P/Churyumov-Gerasimenko observed by the Alice Far-ultraviolet Spectrograph on Rosetta

Alice is a far-ultraviolet imaging spectrograph onboard Rosetta that, amongst multiple objectives, is designed to observe emissions from various atomic and molecular species from within the coma of comet 67P/Churyumov-Gerasimenko. The initial observations, made following orbit insertion in August 2014, showed emissions of atomic hydrogen and oxygen spatially localized close to the nucleus and attributed to photoelectron impact dissociation of H2O vapor. Weaker emissions from atomic carbon were subsequently detected and also attributed to electron impact dissociation, of CO2, the relative H I and C I line intensities reflecting the variation of CO2 to H2O column abundance along the line-of-sight through the coma. Beginning in mid-April 2015, Alice sporadically observed a number of outbursts above the sunward limb characterized by sudden increases in the atomic emissions, particularly the semi-forbidden O I 1356 multiplet, over a period of 10-30 minutes, without a corresponding enhancement in long wavelength solar reflected light characteristic of dust production. A large increase in the brightness ratio O I 1356/O I 1304 suggests O2 as the principal source of the additional gas. These outbursts do not correlate with any of the visible images of outbursts taken with either OSIRIS or the navigation camera. Beginning in June 2015 the nature of the Alice spectrum changed considerably with CO Fourth Positive band emission observed continuously, varying with pointing but otherwise fairly constant in time. However, CO does not appear to be a major driver of any of the observed outbursts.Comment: 6 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter

Improving the Aerospace Capstone Design Experience Through Simulation Based Learning

A key role of universities is to prepare students to work in their chosen profession upon completion of their degree program. Engineering capstone design courses are often the only required courses that challenge students to draw on nearly all of the students’ previous collegiate learning experiences and to synthesize and apply these to creating a new solution to an engineering problem. Aside from internship and co-op experiences, these are often the first courses that expose engineering students to some of the technical and political issues that they will often face in their professional engineering careers. Industry often looks at these design experiences in addition to work experience when evaluating new graduates. While beneficial, there remains a perceived disconnect between what academia is producing and what industry is seeking. Industry is seeking ‘engineers’ who are well versed in the application of science to problem solving whereas academia is producing ‘engineer scientists’ who are well versed in the science, but lacking in the application of knowledge gained through experience. While some context-based learning opportunities are emerging much earlier in the engineering curriculum, the needs and means to provide such experiences remain limited. This paper discusses a pilot study that was conducted during the first term of a two term capstone design class in aerospace engineering aircraft design at Virginia Tech. The study explored the educational impact of utilizing realism and simulation to introduce the aircraft design process with the aim of determining if such an approach could help remedy the academia/industry disconnect and at the same time make for an engaging design experience for the students. Results indicate that the use of simulation was welcomed by the participants of the study and can help prepare students to think as working design professionals, not limited by the generic design solutions often found in academic de-contextualized design problems

IS Journal Quality Assessment Using the Author Affiliation Index

Research productivity is one means by which academic units attain legitimacy within their institutional milieu and make their case for resources. Journal quality assessment is an important component for assessing faculty research productivity. We introduce the Author Affiliation Index (AAI), a simple method for assessing journal quality, to the IS domain. Essentially, the AAI of a journal is the percentage of academic authors publishing in that journal who are affiliated with a base set of high-quality academic institutions. Besides explaining the AAI, we demonstrate its use with a set of well-known IS journals, discuss its rankings vis-à-vis those resulting from other methods, and provide an example of how the basic AAI approach can be modified by changing the base school set that is used to define journal quality. The AAI has a number of advantages. First, it is a simple, low cost and transparent method for assessing any journal given a base school set. Second, it provides a consistent ranking of journals, particularly of those beyond the top consensus journals where less consistency is achieved with other measures. Third, it enables new journals to be rapidly assessed against more established ones without the lags or costs of other measures. The AAI provides another indicator of journal quality that is different from surveys and citation analyses

The Ultraviolet Imaging Telescope: Instrument and Data Characteristics

The Ultraviolet Imaging Telescope (UIT) was flown as part of the Astro observatory on the Space Shuttle Columbia in December 1990 and again on the Space Shuttle Endeavor in March 1995. Ultraviolet (1200-3300 Angstroms) images of a variety of astronomical objects, with a 40 arcmin field of view and a resolution of about 3 arcsec, were recorded on photographic film. The data recorded during the first flight are available to the astronomical community through the National Space Science Data Center (NSSDC); the data recorded during the second flight will soon be available as well. This paper discusses in detail the design, operation, data reduction, and calibration of UIT, providing the user of the data with information for understanding and using the data. It also provides guidelines for analyzing other astronomical imagery made with image intensifiers and photographic film.Comment: 44 pages, LaTeX, AAS preprint style and EPSF macros, accepted by PAS