1,811 research outputs found
Inlet spillage drag tests and numerical flow-field analysis at subsonic and transonic speeds of a 1/8-scale, two-dimensional, external-compression, variable-geometry, supersonic inlet configuration
Accurate spillage drag and pressure data are presented for a realistic supersonic inlet configuration. Results are compared with predictions from a finite-differencing, inviscid analysis computer procedure. The analytical technique shows good promise for the evaluation of inlet drag, but necessary refinements were identified. A detailed description of the analytical procedure is contained in the Appendix
Determination of Interface Atomic Structure and Its Impact on Spin Transport Using Z-Contrast Microscopy and Density-Functional Theory
We combine Z-contrast scanning transmission electron microscopy with
density-functional-theory calculations to determine the atomic structure of the
Fe/AlGaAs interface in spin-polarized light-emitting diodes. A 44% increase in
spin-injection efficiency occurs after a low-temperature anneal, which produces
an ordered, coherent interface consisting of a single atomic plane of
alternating Fe and As atoms. First-principles transport calculations indicate
that the increase in spin-injection efficiency is due to the abruptness and
coherency of the annealed interface.Comment: 16 pages (including cover), 4 figure
Large igneous provinces track fluctuations in subaerial exposure of continents across the Archean–Proterozoic transition
Geological observations and numerical models imply that Archean continents were mostly submarine. In contrast, approximately one third of modern earth's surface area consists of subaerial continental crust. To temporally constrain changes in the subaerial exposure of continents, we evaluate the eruptive environment (submarine vs subaerial) of 3.4–2.0 Ga continental large igneous provinces (LIPs). Our results indicate that up until 2.4 Ga LIPs predominantly erupted onto submerged continents. This period of low freeboard was punctuated by local subaerial eruptions at 2.8–2.7 Ga and 2.5 Ga. From 2.4 Ga–2.2 Ga, extensive subaerial continental volcanism is recorded in six different cratons, supporting widespread subaerial continents at this time. An increase in exposed continental crust significantly impacts atmospheric and oceanic geochemical cycles and the supply of nutrients for marine bioproductivity. Thus, the 2.4–2.2 Ga high-freeboard conditions may have triggered the earliest global glaciation event and the first significant rise of atmospheric oxygen
Spatial Distribution of Competing Ions around DNA in Solution
The competition of monovalent and divalent cations for proximity to negatively charged DNA is of biological importance and can provide strong constraints for theoretical treatments of polyelectrolytes. Resonant x-ray scattering experiments have allowed us to monitor the number and distribution of each cation in a mixed ion cloud around DNA. These measurements provide experimental evidence to support a general theoretical prediction: the normalized distribution of each ion around polyelectrolytes remains constant when ions are mixed at different ratios. In addition, the amplitudes of the scattering signals throughout the competition provide a measurement of the surface concentration parameter that predicts the competition behavior of these cations. The data suggest that ion size needs to be taken into account in applying Poisson-Boltzmann treatments to polyelectrolytes such as DNA
Demonstration of Cross-Reactive Antibodies to Smooth Gram-Negative Bacteria in Antiserum to Escherichia coli J5
We investigated the discrepancy between the broad cross-protection against gram-negative infections afforded by antiserum to Escherichia coli J5 and its apparently narrow cross-reactivity in vitro. Rabbits immunized with J5 bacteria produced antibodies to both the J5 lipopolysaccharide (LPS; titer by ELISA, 1:60,000) and LPS from the Re mutant of Salmonella minnesota (i.e., to the ketodeoxyoctonate [KDO] and lipid A determinants; titer, 1:3,200). In highly diluted antiserum, titers of antibody to J5 LPS were reduced by 28%-41% after adsorption with seven strains of smooth gram-negative bacteria and by only 4% after adsorption with the Re mutant. Smooth gram-negative bacteria adsorbed virtually all antibody to Re LPS. Therefore, rabbit antiserum to J5 contains type-specific antibodies to core determinants distal to KDO that can obscure highly cross-reactive antibodies to lipid A-KDO in vitro. Cross-reactive antibodies are demonstrable by adsorption with whole bacteria at limiting concentrations of antibod
Accessibility, interdisciplinarity and practice:The benefits and challenges of hosting an online, interdisciplinary conference on singing
In May 2020, the Spheres of Singing conference, which was initially intended as an in-person event,
was instead hosted online. A key ambition was to make the conference accessible for both
practitioners and researchers from various disciplines. The conference exceeded in its aim in several
ways. It was free and featured contributions from around the world, including 45 presentations, four
workshops, six open discussions and three lecture-recitals. The interdisciplinary array of sessions
included: health and wellbeing, practice research, musicology, teaching, conducting, pedagogy, and
virtual choirs. In terms of attendee interest, all 450 live attendance tickets sold out in 24 hours, with
additional tickets made available to allow asynchronous attendance. Such enthusiasm demonstrates
an interdisciplinary event on singing was both timely and necessary.
The organisers developed a survey to gather feedback, measure impact, and help determine future
directions. A significant finding is that practitioners were motivated to attend, specifically because it
was an online event. However, there were challenges caused by moving the conference online,
particularly when it came to relying on technology and integrating live singing activities. By analysing
the feedback gathered from delegates, the article will consider three areas: creating an inviting event
for practitioners and researchers, technological challenges when hosting an online conference on
singing, and integrating live, synchronous singing activities into an online conference
Silver-Zinc Battery Separator Material Development
Ethylene/methyl acrylate copolymer synthesis for silver-zinc battery separator
One-Step Processing of Spinel Ferrites via the High-Energy Ball Milling of Binary Oxides
MnZn ferrites have been produced via the high-energy ball milling of binary oxide precursors. The milled ferrites have a nonequilibrium cation site distribution, with an unusually high population of Zn cations on the octahedral sites. The particle size distribution drops precipitously with milling time from 60±1 to ∼14±1 nm at 10 h, but increases to 18.5±1 nm after long durations (20–40 h) concurrent with the formation of nearly pure ferrite. A 1 h anneal at 673 K facilitates a redistribution of cations to their near equilibrium sites. This processing approach circumvents the need for deleterious high-temperature heat treatments that often lead to nonstoichiometries in the resulting ferrites
Polymorphism in TGFB1 is associated with worse non-relapse mortality and overall survival after stem cell transplantation with unrelated donors.
Transforming growth factor beta-1, encoded by the TGFB1 gene, is a cytokine that plays a central role in many physiological and pathogenic processes. We have sequenced TGFB1 regulatory region and assigned allelic genotypes in a large cohort of hematopoietic stem cell transplantation patients and donors. In this study, we analyzed 522 unrelated donor-patient pairs and examined the combined effect of all the common polymorphisms in this genomic region. In univariate analysis, we found that patients carrying a specific allele, 'p001', showed significantly reduced overall survival (5-year overall survival 30.7% for p001/ p001 patients vs. 41.6% others; P=0.032) and increased non-relapse mortality (1-year nonrelapse mortality: 39.0% vs. 25.4%; P=0.039) after transplantation. In multivariate analysis, the presence of a p001/ p001 genotype in patients was confirmed as an independent factor for reduced overall survival [hazard ratio=1.53 (1.04-2.24); P=0.031], and increased non-relapse mortality [hazard ratio=1.73 (1.06-2.83); P=0.030]. In functional experiments we found a trend towards a higher percentage of surface transforming growth factor beta-1-positive regulatory T cells after activation when the cells had a p001 allele (P=0.07). Higher or lower production of transforming growth factor beta-1 in the inflammatory context of hematopoietic stem cell transplantation may influence the development of complications in these patients. Findings indicate that TGFB1 genotype could potentially be of use as a prognostic factor in hematopoietic stem cell transplantation risk assessment algorithms
The Glenburgh Orogeny as a record of Paleoproterozoic continent-continent collision
The Gascoyne Province lies at the western end of the Capricorn Orogen, and includes a range of Paleoproterozoic gneisses and metasedimentary basins, known as the Glenburgh Terrane, that are exotic to both the Yilgarn and Pilbara Cratons. Here we present sensitive high-resolution ion microprobe (SHRIMP) U–Pb ages for a variety of detrital zircons and metamorphic zircon and monazite from several of these pre-collisional siliciclastic basins that were deformed and metamorphosed at high metamorphic grade during the Glenburgh Orogeny, when the Yilgarn Craton collided with a previously assembled Pilbara Craton – Glenburgh Terrane. The precursors to the Moogie Metamorphics were deposited sometime between 2240 and 2125 Ma in either a foreland basin to the Ophthalmian Orogeny, or a retro-arc that formed during the collision of the Glenburgh Terrane with the Pilbara Craton. The Quartpot Pelite of the Camel Hills Metamorphics was deposited between 2000 Ma and 1985 Ma as a fore-arc deposit to the Dalgaringa continental margin arc. The Petter Calc-silicate of the Camel Hills Metamorphics was deposited sometime between 2610 and 1965 Ma as part of the Yilgarn Craton passive margin. Metamorphic zircon and monazite ages indicate that continental collision and high-grade metamorphism during the Glenburgh Orogeny (D2g) took place between 1965 Ma and 1950 Ma
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