Direct observations of nucleation in a nondilute multicomponent alloy

The chemical pathways leading to gamma-prime(L1_2)-nucleation from nondilute Ni-5.2 Al-14.2 Cr at.%, gamma(f.c.c.), at 873 K are followed with radial distribution functions and isoconcentration surface analyses of direct-space atom-probe tomographic images. Although Cr atoms initially are randomly distributed, a distribution of congruent Ni3Al short-range order domains (SRO), =0.6 nm, results from Al diffusion during quenching. Domain site occupancy develops as their number density increases leading to Al-rich phase separation by gamma-prime-nucleation, =0.75 nm, after SRO occurs.Comment: 5 pages, 4 figure

MalStone: Towards A Benchmark for Analytics on Large Data Clouds

Developing data mining algorithms that are suitable for cloud computing platforms is currently an active area of research, as is developing cloud computing platforms appropriate for data mining. Currently, the most common benchmark for cloud computing is the Terasort (and related) benchmarks. Although the Terasort Benchmark is quite useful, it was not designed for data mining per se. In this paper, we introduce a benchmark called MalStone that is specifically designed to measure the performance of cloud computing middleware that supports the type of data intensive computing common when building data mining models. We also introduce MalGen, which is a utility for generating data on clouds that can be used with MalStone

Trademark Surveys: An Undulating Path

When a plaintiff alleges trademark infringement or claims that false advertising is likely to confuse or deceive, the pivotal legal question is: how are consumers likely to perceive the mark or advertising? In the early days of trademark litigation, a parade of consumer witnesses, carefully selected by one of the parties to support a trademark claim, would testify about their reactions to a mark. That approach has given way to systematic survey evidence reflecting the responses of a substantial number of consumers selected according to an explicit sampling plan, asked the same questions, and unaware who sponsored the survey. Part I provides a description of the primary legal topics that appear in trademark and deceptive advertising surveys. Part II reviews the recent studies that investigate the presence and influence of surveys in reported infringement decisions, identifying some of the limitations of these studies as a way to describe the role that surveys play in trademark litigation. Part III takes a close look at a sample of the reported cases that did not include survey evidence to begin our assessment of why surveys are or are not submitted in trademark cases. Part IV describes our survey, including a description of our methodology (the full survey instrument appears in an Appendix), questions, and results. Part V offers an explanation of why surveys may be underrepresented in reported cases, and when surveys succeed and fail as persuasive evidence. We analyze the limitations of survey methodology in current trademark litigation identified by our respondents, as well as judicial reactions to surveys that provide clues to the ambivalence of some judges to the surveys presented in court

Direct Measurement of 2D and 3D Interprecipitate Distance Distributions from Atom-Probe Tomographic Reconstructions

Edge-to-edge interprecipitate distance distributions are critical for predicting precipitation strengthening of alloys and other physical phenomena. A method to calculate this 3D distance and the 2D interplanar distance from atom-probe tomographic data is presented. It is applied to nanometer-sized Cu-rich precipitates in an Fe-1.7 at.% Cu alloy. Experimental interprecipitate distance distributions are discussed

Structure and Growth of Core–shell Nanoprecipitates in Al–Er–Sc–Zr–V–Si High-temperature Alloys

Lightweight Sc-containing aluminum alloys exhibit superior mechanical performance at high temperatures due to core–shell, L12-ordered trialuminide nanoprecipitates. In this study, the structure of these nanoprecipitates was studied, using different transmission electron microscopy (TEM) techniques, for an Al–Er– Sc–Zr–V–Si alloy that was subjected to a two-stage overaging heat treatment. Energy-dispersive X-ray spectroscopy of the spherical Al3(Sc, Zr, Er ,V) nanoprecipitates revealed a core–shell structure with an Sc- and Er-enriched core and a Zr-enriched shell, without a clear V outer shell. This structure is stable up to 72% of the absolute melting temperature of Al for extended periods of time. High-angle annular dark-field scanning TEM was used to image the {100} planes of the nanoprecipitates, demonstrating a homogeneous L12-ordered superlattice structure for the entire nanoprecipitates, despite the variations in the concentrations of solute atoms within the unit cells. A possible growth path and compositional trajectory for these nanoprecipitates was proposed using high-resolution TEM observations, where different rod-like structural defects were detected, which are considered to be precursors to the spherical L12-ordered nanoprecipitates. It is also hypothesized that the structural defects could consist of segregated Si; however, this was not possible to verify with HAADF-STEM because of the small differences in Al and Si atomic numbers. The results herein allow a better understanding of how the Al–Sc alloys’ core–shell nanoprecipitates form and evolve temporally, thereby providing a better physical picture for future atomistic structural mappings and simulations

Effects of solute concentrations on kinetic pathways in Ni-Al-Cr alloys

The kinetic pathways resulting from the formation of coherent L12-ordered y'-precipitates in the g-matrix (f.c.c.) of Ni-7.5 Al-8.5 Cr at.% and Ni-5.2 Al-14.2 Cr at.% alloys, aged at 873 K, are investigated by atom-probe tomography (APT) over a range of aging times from 1/6 to 1024 hours; these alloys have approximately the same volume fraction of the y'-precipitate phase. Quantification of the phase decomposition within the framework of classical nucleation theory reveals that the y-matrix solid-solution solute supersaturations of both alloys provide the chemical driving force, which acts as the primary determinant of the nucleation behavior. In the coarsening regime, the temporal evolution of the y'-precipitate average radii and the y-matrix supersaturations follow the predictions of classical coarsening models, while the temporal evolution of the y'-precipitate number densities of both alloys do not. APT results are compared to equilibrium calculations of the pertinent solvus lines determined by employing both Thermo-Calc and Grand-Canonical Monte Carlo simulation.Comment: Submitted to Acta Materialia, June, 200

Loss of Obstetric Services in Rural Appalachia: A Qualitative Study of Community Perceptions

Background: As rural hospitals across the United States increasingly downsize or close, the availability of inpatient obstetric services continues to decline in rural areas. In rural Appalachia, the termination of obstetric services threatens to exacerbate the existing risk of adverse birth outcomes for women and infants, yet less is known about how the cessation of these services affects the broader community. Purpose: The purpose of this paper is to explain how the loss of local obstetric services affects perceptions of healthcare among multi-generational residents of a remote, rural Appalachian community in western North Carolina. Methods: An interdisciplinary team of researchers conducted a thematic analysis of health-related oral history interviews (n=14) that were collected from local residents of a rural, western North Carolina community during the summer of 2019. Results: The closure of a local hospital’s labor and delivery department fostered 1) frustration with the decline in hospital services, 2) perceived increases in barriers to accessing healthcare, and 3) increased medical mistrust. Implications: Findings suggest that the loss of obstetric services in this rural Appalachian community could have broad, negative health implications for all residents, regardless of their age, sex, or ability to bear children. Community-specific strategies are needed to foster trust in the remaining healthcare providers and to increase access to care for local residents. Results serve as formative research to support the development of interventions and policies that effectively respond to all community members’ needs and concerns following the loss of obstetric services in remote Appalachian communities