6,192 research outputs found
What we can learn from magnetic Compton scattering : application to the determination of spin polarization
Studies of spin-resolved electron momentum densities involve the measurement of the so-called magnetic Compton profile. This is a one-dimensional projection of the electron momentum distribution of only those electrons that contribute to the spin moment of a sample. The technique is applicable to ferri- and ferromagnetic materials. The profile is obtained via the inelastic 'Compton' scattering of high energy X-rays. Since electrons originating from different atomic orbitals have specific momentum densities, it is often possible to determine the origin of the magnetism present. Typically, interpretation requires the use of electronic structure calculations using molecular orbital and band structure approaches. Here, we highlight the application of the technique to the determination of the Fermi level spin polarization, the knowledge of which is important to the development of novel spintronic materials
Structural/thermal considerations for design of large space platform structures
A method is described for placing a large, STS-compatible platform on orbit utilizing a construction method employing both deployable and erectable structures. A multifunctional mechanism is used for deployable structures and an on-orbit assembly is used for erectable structures. Also analyses are discussed which assess the thermal distortion of a simple open truss and a more complex truss
Probability of Causation for Lung Cancer After Exposure to Radon Progeny: A Comparison of Models and Data
The estimates of lung cancer risk due to the exposure to radon decay products are based on different data sets from underground mining and on different mathematical models that are used to fit the data. Diagrams of the excess relative rate per 100 working level months in its dependence on age at exposure and age attained are shown to be a useful tool to elucidate the influence that is due to the choice of the model, and to assess the differences between the data from the major western cohorts and those from the Czech uranium miners. It is seen that the influence of the choice of the model is minor compared to the difference between the data sets. The results are used to derive attributable lifetime risks and probabilities of causation for lung cancer following radon progeny exposures
Outcasts of Empire
"Outcasts of Empire unveils the causes and consequences of capitalism’s failure to “batter down all Chinese walls” in modern Taiwan. Adopting micro- and macrohistorical perspectives, Paul D. Barclay argues that the interpreters, chiefs, and trading-post operators who mediated state-society relations on Taiwan’s “savage border” during successive Qing and Japanese regimes rose to prominence and faded to obscurity in concert with a series of “long nineteenth century” global transformations. Superior firepower and large economic reserves ultimately enabled Japanese statesmen to discard mediators on the border and sideline a cohort of indigenous headmen who played both sides of the fence to maintain their chiefly status. Even with reluctant “allies” marginalized, however, the colonial state lacked sufficient resources to integrate Taiwan’s indigenes into its disciplinary apparatus. The colonial state therefore created the Indigenous Territory, which exists to this day as a legacy of Japanese imperialism, local initiatives, and the global commodification of culture.
Simplified thermal estimation techniques for large space structures
A tool for making rapid estimates of the response of space structures to thermal environments encountered in earth orbits is provided for the designer of these structures. Charts giving heating rates and temperatures for certain typical large spacecraft structural elements are provided. Background information for spacecraft thermal design considerations is presented. Environments, requirements, thermal control techniques, design guidelines, and approaches available for more detailed thermal response analysis are discussed
High-Spatial-Resolution K-Band Imaging of Select K2 Campaign Fields
NASA's K2 mission began observing fields along the ecliptic plane in 2014.
Each observing campaign lasts approximately 80 days, during which
high-precision optical photometry of select astrophysical targets is collected
by the Kepler spacecraft. Due to the 4 arcsec pixel scale of the Kepler
photometer, significant blending between the observed targets can occur
(especially in dense fields close to the Galactic plane). We undertook a
program to use the Wide Field Camera (WFCAM) on the 3.8 m United Kingdom
InfraRed Telescope (UKIRT) to collect high-spatial-resolution near-infrared
images of targets in select K2 campaign fields, which we report here. These 0.4
arcsec resolution K-band images offer the opportunity to perform a variety of
science, including vetting exoplanet candidates by identifying nearby stars
blended with the target star and estimating the size, color, and type of
galaxies observed by K2.Comment: 2 pages, Published by Research Notes of the American Astronomical
Societ
A Survey of the Czechoslovak Follow-up of Lung Cancer Mortality in Uranium Miners
The major Czechoslovak cohort of uranium miners (S-cohort) is surveyed in terms of diagrams illustrating dependences on calendar year, age, and exposure to radon and radon progeny. An analysis of the dose dependence of lung cancer mortality is performed by nonparametric and, subsequently, by parametric methods. In the first step, two-dimensional isotonic regression is employed to derive the lung cancer mortality rate and the relative excess risk as functions of age attained and of lagged cumulated exposure. In a second step, analytical fits in terms of relative risk models are derived. The treatment is largely analogous to the methods applied by the BEIR IV Committee to other major cohorts of uranium miners. There is a marked dependence of the excess risk on age attained and on time since exposure. A specific characteristic of the Czechoslovak data is the nonlinearity of the dependence of the lung cancer excess risk on the cumulated exposure; exposures on the order of 100 working level months or less appear to be more effective per working level month than larger exposures but, in the absence of an internal control group, this cannot be excluded to be due to confounders such as smoking or environmental exposures. A further notable observation is the association of larger excess risks with longer protraction of the exposures
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