29,784 research outputs found
Analysis of ZDDP content and thermal decomposition in motor oils using NAA and NMR
Zinc dialkyldithiophosphates (ZDDPs) are one of the most common anti-wear
additives present in commercially-available motor oils. The ZDDP concentrations
of motor oils are most commonly determined using inductively coupled plasma
atomic emission spectroscopy (ICP-AES). As part of an undergraduate research
project, we have determined the Zn concentrations of eight
commercially-available motor oils and one oil additive using neutron activation
analysis (NAA), which has potential for greater accuracy and less sensitivity
to matrix effects as compared to ICP-AES. The 31P nuclear magnetic resonance
(31P-NMR) spectra were also obtained for several oil additive samples which
have been heated to various temperatures in order to study the thermal
decomposition of ZDDPs.Comment: Manuscript has been accepted for publication in Physics Procedia as
part of the proceedings of the 23rd International Conference on Application
of Accelerators in Research and Industry (CAARI 2014
A systematic review of reported reassortant viral lineages of influenza A
BACKGROUND: Most previous evolutionary studies of influenza A have focussed on genetic drift, or reassortment of specific gene segments, hosts or subtypes. We conducted a systematic literature review to identify reported claimed reassortant influenza A lineages with genomic data available in GenBank, to obtain 646 unique first-report isolates out of a possible 20,781 open-access genomes. RESULTS: After adjusting for correlations, only: swine as host, China, Europe, Japan and years between 1997 and 2002; remained as significant risk factors for the reporting of reassortant viral lineages. For swine H1, more reassortants were observed in the North American H1 clade compared with the Eurasian avian-like H1N1 clade. Conversely, for avian H5 isolates, a higher number of reported reassortants were observed in the European H5N2/H3N2 clade compared with the H5N2 North American clade. CONCLUSIONS: Despite unavoidable biases (publication, database choice and upload propensity) these results synthesize a large majority of the current literature on novel reported influenza A reassortants and are a potentially useful prerequisite to inform further algorithmic studies. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12879-015-1298-9) contains supplementary material, which is available to authorized users
What shapes the far-infrared spectral energy distributions of galaxies?
To explore the connection between the global physical properties of galaxies
and their far-infrared (FIR) spectral energy distributions (SEDs), we study the
variation in the FIR SEDs of a set of hydrodynamically simulated galaxies that
are generated by performing dust radiative transfer in post-processing. Our
sample includes both isolated and merging systems at various stages of the
merging process and covers infrared (IR) luminosities and dust masses that are
representative of both low- and high-redshift galaxies. We study the FIR SEDs
using principle component analysis (PCA) and find that 97\% of the variance in
the sample can be explained by two principle components (PCs). The first PC
characterizes the wavelength of the peak of the FIR SED, and the second encodes
the breadth of the SED. We find that the coefficients of both PCs can be
predicted well using a double power law in terms of the IR luminosity and dust
mass, which suggests that these two physical properties are the primary
determinants of galaxies' FIR SED shapes. Incorporating galaxy sizes does not
significantly improve our ability to predict the FIR SEDs. Our results suggest
that the observed redshift evolution in the effective dust temperature at fixed
IR luminosity is not driven by geometry: the SEDs of ultraluminous
IR galaxies (ULIRGs) are cooler than those of local ULIRGs not because the
high-redshift galaxies are more extended but rather because they have higher
dust masses at fixed IR luminosity. Finally, based on our simulations, we
introduce a two-parameter set of SED templates that depend on both IR
luminosity and dust mass.Comment: Submitted to ApJ, comments welcom
Improving outcomes-based engineering education in Australia
Graduate attributes are now a ubiquitous feature of higher education in Australia and internationally, and have been part of engineering education for more than a decade. The idea of graduate attributes is an apparently simple concept, focusing on educational outcomes, rather than inputs and process. While there is evidence of some benefits in engineering education arising from the introduction of outcomes-based accreditation, there is also evidence of many short-comings of the graduate attributes approach. There would be significant value in Engineers Australia providing additional discipline-specific guidance on attribute development. There would be significant value in Engineers Australia simplifying and consolidating the current multi-document accreditation system. A genuinely outcomes-based accreditation system would be based (only) on the demonstrated individual student attainment of appropriate graduate attributes, which might be delivered/gained by a range of means, including distance education. To fully meet the letter and spirit of the law for accreditation, programs will need to adopt some method of certification of individual student attainment of graduate attributes - one such method would be the use of student portfolios.<br /
Understanding the Transition between High School and College Mathematics and Science
Mathematics and science education is gaining increasing recognition as key for the well-being of individuals and society. Accordingly, the transition from high school to college is particularly important to ensure that students are prepared for college mathematics and science. The goal of this study was to understand how high school mathematics and science course-taking related to performance in college. Specifically, the study employed a nonparametric regression method to examine the relationship between high school mathematics and science courses, and academic performance in college mathematics and science courses. The results provide some evidence pertaining to the positive benefits from high school course-taking. Namely, students who completed high school trigonometry and lab-based chemistry tended to earn higher grades in college algebra and general chemistry, respectively. However, there was also evidence that high school coursework in biology and physics did not improve course performance in general biology and college physics beyond standardized test scores. Interestingly, students who completed high school calculus earned better grades in general biology. The implications of the findings are discussed for high school curriculum and alignment in standards between high schools and colleges
MGGPOD: a Monte Carlo Suite for Modeling Instrumental Line and Continuum Backgrounds in Gamma-Ray Astronomy
Intense and complex instrumental backgrounds, against which the much smaller
signals from celestial sources have to be discerned, are a notorious problem
for low and intermediate energy gamma-ray astronomy (~50 keV - 10 MeV).
Therefore a detailed qualitative and quantitative understanding of instrumental
line and continuum backgrounds is crucial for most stages of gamma-ray
astronomy missions, ranging from the design and development of new
instrumentation through performance prediction to data reduction. We have
developed MGGPOD, a user-friendly suite of Monte Carlo codes built around the
widely used GEANT (Version 3.21) package, to simulate ab initio the physical
processes relevant for the production of instrumental backgrounds. These
include the build-up and delayed decay of radioactive isotopes as well as the
prompt de-excitation of excited nuclei, both of which give rise to a plethora
of instrumental gamma-ray background lines in addition to continuum
backgrounds. The MGGPOD package and documentation are publicly available for
download from http://sigma-2.cesr.fr/spi/MGGPOD/.
We demonstrate the capabilities of the MGGPOD suite by modeling high
resolution gamma-ray spectra recorded by the Transient Gamma-Ray Spectrometer
(TGRS) on board Wind during 1995. The TGRS is a Ge spectrometer operating in
the 40 keV to 8 MeV range. Due to its fine energy resolution, these spectra
reveal the complex instrumental background in formidable detail, particularly
the many prompt and delayed gamma-ray lines. We evaluate the successes and
failures of the MGGPOD package in reproducing TGRS data, and provide
identifications for the numerous instrumental lines.Comment: 60 pages, 13 figures, 7 tables, accepted for publication in ApJ
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