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Background
The Institute for Healthcare Improvement (IHI) hosts the annual IHI Forum, a conference that has been the home of quality improvement in health care for over 30 years. In prior years, the Scientific Symposium was a standalone pre-conference event featuring the science of improvement in health and health care. In the early days and years of the COVID pandemic, the Scientific Symposium transitioned from an in-person pre-conference event to a fully virtual event, first as a pre-conference event and then running in parallel with other IHI Forum virtual events. This year marks the first year in which the Scientific Symposium will be fully integrated within the in-person IHI Forum.
Journal Article
Influence of Fe Vacancy on the Bonding Properties of γ-Fe Interfaces: A Theoretical Study
Here, the effects of Fe vacancy defects on the bonding properties of γ-Fe (111)/α-Al[sub.2]O[sub.3] (0001) interfaces are studied in depth at the atomic and electronic levels using first-principles calculations. The first (V[sub.1]), second (V[sub.2]), third (V[sub.3]), and fourth (V[sub.4]) layers of vacancy structures within the Fe substrate, as well as the ideal Fe/Al[sub.2]O[sub.3] interface structure, are proposed and contrasted, including their thermodynamic parameters and atomic/electronic properties. The results demonstrate that the presence of vacancies in the first atomic layer of Fe deteriorates the interfacial bonding strength, whereas vacancies situated in the third layer enhance the interfacial bonding strength. The effect of vacancy beyond the third layer becomes negligible. This occurs mainly because vacancy defects at different positions induce the relaxation behavior of atoms, resulting in bond-breaking and bond-forming reactions at the interface. Following that, the formation process of vacancies can cause the transfer and rearrangement of the electrons at the interface. This process leads to significant changes in the charge concentration of the interfaces, where V[sub.3] is the largest and V[sub.1] is the smallest, indicating that the greater the charge concentration, the stronger the bonding strength of the interface. Furthermore, it is discovered that vacancy defects can induce new electronic orbital hybridization between Fe and O at the interface, which is the fundamental reason for changes in the properties of the interface. Interestingly, it is also found that more electronic orbital hybridization will strengthen the bonding performance of the interface. It seems, then, that the existence of vacancy defects not only changes the electronic environment of the Fe/Al[sub.2]O[sub.3] interface but also directly affects the bonding properties of the interface.
Journal Article
LiteBIRD: A Satellite for the Studies of B-Mode Polarization and Inflation from Cosmic Background Radiation Detection
LiteBIRD is a candidate satellite for a strategic large mission of JAXA. With its expected launch in the middle of the 2020s with a H3 rocket, LiteBIRD plans to map the polarization of the cosmic microwave background radiation over the full sky with unprecedented precision. The full success of LiteBIRD is to achieve
δ
r
<
0.001
, where
δ
r
is the total error on the tensor-to-scalar ratio
r
. The required angular coverage corresponds to
2
≤
ℓ
≤
200
, where
ℓ
is the multipole moment. This allows us to test well-motivated cosmic inflation models. Full-sky surveys for 3 years at a Lagrangian point L2 will be carried out for 15 frequency bands between 34 and 448 GHz with two telescopes to achieve the total sensitivity of 2.5
μ
K arcmin with a typical angular resolution of 0.5
∘
at 150 GHz. Each telescope is equipped with a half-wave plate system for polarization signal modulation and a focal plane filled with polarization-sensitive TES bolometers. A cryogenic system provides a 100 mK base temperature for the focal planes and 2 K and 5 K stages for optical components.
Journal Article
An absorption profile centred at 78 megahertz in the sky-averaged spectrum
The 21-cm absorption profile is detected in the sky-averaged radio spectrum, but is much stronger than predicted, suggesting that the primordial gas might have been cooler than predicted.
An absorption profile in the sky
As the first stars heated hydrogen in the early Universe, the 21-cm hyperfine line—an astronomical standard that represents the spin-flip transition in the ground state of atomic hydrogen—was altered, causing the hydrogen gas to absorb photons from the microwave background. This should produce an observable absorption signal at frequencies of less than 200 megahertz (MHz). Judd Bowman and colleagues report the observation of an absorption profile centred at a frequency of 78 MHz that is about 19 MHz wide and 0.5 kelvin deep. The profile is generally in line with expectations, although it is deeper than predicted. An accompanying paper by Rennan Barkana suggests that baryons were interacting with cold dark-matter particles in the early Universe, cooling the gas more than had been expected.
After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz
1
. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions
2
. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected. Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude
3
. The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.
Journal Article
Effects of agricultural activities on long-term accumulations of .sup.226Ra and .sup.210Po in topsoil
In this study, long-term changes in radioactivity levels in the agricultural soil were assessed by a method in which the major processes contributing to the accumulations of radionuclides in the topsoil were taken into account. Four agricultural regions with different crops and agricultural conditions were investigated. The results indicated that long-term cultivation caused the accumulations of .sup.226Ra and .sup.210Po in the topsoil and the rates correlated strongly to plant types, fertilization, and irrigation features. This research is used as the pre-primary base to decide the cultivation method that is relevant to the selection of plant varieties, fertilization and irrigation methods.
Journal Article
