Multiplier Sequences for Simple Sets of Polynomials

In this paper we give a new characterization of simple sets of polynomials B with the property that the set of B-multiplier sequences contains all Q-multiplier sequence for every simple set Q. We characterize sequences of real numbers which are multiplier sequences for every simple set Q, and obtain some results toward the partitioning of the set of classical multiplier sequences

Spectrum imaging of complex nanostructures using DualEELS: I. digital extraction replicas

This paper shows how it is possible to use Dual Electron Energy Loss Spectroscopy (DualEELS) to digitally extract spectrum images for one phase of interest in a complex nanostructured specimen. The specific cases studied here concern Nb or V precipitates, a few nanometres in size, in high manganese steels. The procedures outlined allow the extraction of the precipitate signal from the Fe–Mn matrix, as well as correction for surface oxide and any surface carbon contamination. The resulting precipitate-only spectrum images are then suitable for quantitative analysis of the precipitate chemistry. This procedure results in much improved background shapes under all edges of interest, mainly as a result of the removal of the extended electron loss fine structure (EXELFS) from the elements in the matrix. This allows the reliable extraction of even tiny quantities of elements, such as low levels of nitrogen in some carbide precipitates. As well as being relevant to precipitation in steels, these techniques will be widely applicable to the separation of chemically-distinct phases in complex nanostructured samples, and can be viewed as a digital version of the extraction replica technique

Submitting to MedEdPORTAL: Do it right the first time

Presented as a Small Group/Roundtable Discussion at 2020 IUSM Education Day.Medical educators at Indiana University School of Medicine (IUSM) are encouraged to publish in MedEdPORTAL: The Journal of Teaching and Learning Resources. Published by the Association of American Medical Colleges (AAMC), MedEdPORTAL is a peer-reviewed, open-access journal for medical education scholarship. These publications contain complete curricula, including objectives, instructor guides, slides, and assessments, ready to be implemented in the classroom. When faculty members apply for promotion, MedEdPORTAL can demonstrate the quality of their work through peer-review, citation counts, and other usage reports. Despite submitting high quality learning modules, medical educators receive rejections from the MedEdPORTAL 62% of time. Reasons for rejection include insufficient educational context and assessment, mismatch of educational objectives and instructional content, and failure to build on existing curricula. Of immediately rejected submissions, 90% also have copyright issues. MedEdPORTAL is a member of the Open Access Scholarly Publishers Association (OASPA) and therefore has strict requirements for copyright and licensing images in the education materials. These requirements are difficult to navigate. For faculty who are not familiar with copyright and licensing, these barriers can be frustrating enough to deter them from submitting curricula. This workshop introduced MedEdPORTAL, described the submission process, and shared our strategies for putting together a successful submission. By the end of the workshop, participants were able to: • Identify curricula they have developed that would fit with the goals of MedEdPORTAL’s publishers • Use template to complete the Educational Summary Report (ESR) • Classify content as that which requires copyright permission, is in the public domain, or has a Creative Commons license • Navigate the process of manuscript submission and revisio

Electron angular distributions above the dayside auroral oval

An electrostatic analyzer was employed on the Ariel 4 satellite to determine pitch angle distributions of electron intensities over the dayside auroral oval. Two major precipitation zones were encountered: an equatorward zone of broad spectra with intensities of approximately 1000 electrons/(sq cm-sec-sr-eV) and a poleward zone, the polar cusp, with intensities typical of those of the magnetosheath. Angular distributions within the equatorward zone are generally isotropic outside of the atmospheric backscatter cone. The precipitation mechanism appears to be pitch angle scattering near the distant magnetic equator. In contrast, pitch angle distributions within the polar cusp are often found to be strongly field aligned with intensities within the atmospheric loss cone greater by factors of approximately 10 than the mirroring intensities. These distributions are qualititatively similar to those for the inverted V precipitation events at later local times, and probably share a common acceleration mechanism with the inverted V phenomenon

Energization pf polar-cusp electrons at the noon meridian

Observations gained with an electrostatic analyzer on board the low altitude, polar orbiting Aeriel 4 satellite demonstrate that the directional, differential spectra of polar-cusp electron intensities are regulated by the sign of the interplanetary magnetic field (IMF) elevation angle. In the energy range 200 is approximately less than E is approximately less than 700 eV, spectra of polar cusp electron intensities were not observed to respond to changes in the sign of the IMF elevation angle. At greater densities, spectra were found to be significantly harder when the IMF angle of elevation was greater than 0 deg, with a factor of approximately 10 typical for 2-keV electron intensities. These enhanced intensities appear to be localized within approximately a one hour sector of magnetic local time centered on the noon meridian

Getting the most out of a post-column EELS spectrometer on a TEM/STEM by optimising the optical coupling

Ray tracing is used to find improved set-ups of the projector system of a JEOL ARM 200CF TEM/STEM for use in coupling it to a Gatan 965 Quantum ER EELS system and to explain their performance. The system has a probe aberration corrector but no image corrector. With the latter, the problem would be more challenging. The agreement between the calculated performance and that found experimentally is excellent. At 200kV and using the 2.5mm Quantum entrance aperture, the energy range over which the collection angle changes by a maximum of 5% from that at zero loss has been increased from 1.2keV to 4.7keV. At lower accelerating voltages, these energy ranges are lower e.g. at 80kV they are 0.5keV and 2.0keV respectively. The key factors giving the improvement are an increase in the energy-loss at which the projector cross-over goes to infinity and a reduction of the combination aberrations that occur in a lens stack. As well as improving the energy-loss range, the new set-ups reduce spectrum artefacts and minimise the motion of the diffraction pattern at low STEM magnification for electrons that have lost energy. Even if making the pivot points conjugate with the film plane gives no motion for zero-loss electrons, there will be motion for those electrons that have lost energy, leading to a false sense of security when performing spectrum imaging at low magnifications. De-scanning of the probe after the objective lens is a better way of dealing with this problem

Accurate measurement of absolute experimental inelastic mean free paths and EELS differential cross-sections

Methods are described for measuring accurate absolute experimental inelastic mean free paths and differential cross-sections using DualEELS. The methods remove the effects of surface layers and give the results for the bulk materials. The materials used are VC0.83,TiC0.98,VN0.97and TiN0.88but the method should be applicable to a wide range of materials. The data were taken at 200 keVusing a probe half angle of 29mradand a collection angle of 36mrad. The background can be subtracted from under the ionisation edges, which can then be separated from each other. This is achieved by scaling Hartree-Slater calculated cross-sections to the edges in the atomic regions well above the threshold. The average scaling factors required are 1.00 for the non-metal K-edges and 1.01 for the metal L-edges (with uncertainties of a few per cent). If preliminary measurements of the chromatic effects in the post-specimen lenses are correct, both drop to 0.99. The inelastic mean free path for TiC0.98 was measured as 103.6±0.5 nm compared to the prediction of 126.9 nm based on the widely used Iakoubovskii parameterisation