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Renin-Angiotensin-Aldosterone System, Glucose Metabolism and Incident Type 2 Diabetes Mellitus: MESA.
Background Mechanistic studies suggest that aldosterone impairs glucose metabolism. We investigated the cross-sectional associations of aldosterone and plasma renin activity with fasting plasma glucose, insulin resistance ( IR ), β-cell function, and longitudinal association with incident diabetes mellitus among adults in MESA (the multiethnic study of atherosclerosis) prospective cohort study. Methods and Results Homeostatic model assessment of IR ( HOMA 2- IR ) and HOMA 2-β were used to estimate IR and β-cell function, respectively. Incident diabetes mellitus was defined as fasting plasma glucose ≥126 mg/dL or anti-diabetic medication use at follow-up. Linear regression was used to examine cross-sectional associations of aldosterone with fasting plasma glucose, HOMA 2- IR and HOMA 2-β; Cox regression was used to estimate hazard ratios ( HR ) for incident diabetes mellitus with multivariable adjustment. There were 116 cases of incident diabetes mellitus over 10.5 years among 1570 adults (44% non-Hispanic white, 13% Chinese American, 19% Black, 24% Hispanic American, mean age 64±10 years, 51% female). A 100% increase in log-aldosterone was associated with a 2.6 mg/dL higher fasting plasma glucose, 15% higher HOMA 2- IR and 6% higher HOMA 2-β ( P<0.01). A 1- SD increase in log-aldosterone was associated with a 44% higher risk of incident diabetes mellitus ( P<0.01) with the greatest increase of 142% ( P<0.01) observed in Chinese Americans ( P for interaction=0.09 versus other ethnicities). Similar cross-sectional findings for log-plasma renin activity existed, but log-plasma renin activity was not associated with incident diabetes mellitus after full adjustment. Conclusions Aldosterone is associated with glucose homeostasis and diabetes mellitus risk with graded associations among Chinese Americans and blacks, suggesting that pleiotropic effects of aldosterone may represent a modifiable mechanism in diabetes mellitus pathogenesis with potential racial/ethnic variation
Observation of the Origin of d0 Magnetism in ZnO Nanostructures Using X-ray-based Microscopic and Spectroscopic Techniques
[[abstract]]Efforts have been made to elucidate the origin of d(0) magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子
Stress fluctuation, crack renucleation and toughening in layered materials
It has been established that contrast in the elastic properties can lead to enhancement of fracture toughness in heterogeneous materials. Focussing on layered materials as a model system, we show that this enhancement is a result of two distinct phenomena – first, fluctuations in stress leading to regions where the stress intensity at the crack is considerably smaller than that of the macroscopically applied value; and second, the lack of stress intensity when a crack is at a compliant to stiff interface thereby requiring renucleation. Using theoretical, computational and experimental methods, we study two geometries – a layered material and a layered material with a narrow channel – to separate the two phenomena. The stress fluctuation is present in both, but renucleation is present only in the layered medium. We provide quantitative estimates for the enhanced toughness
Systematic errors in strong gravitational lensing reconstructions, a numerical simulation perspective
We present the analysis of a sample of twenty-four SLACS-like galaxy-galaxy
strong gravitational lens systems with a background source and deflectors from
the Illustris-1 simulation. We study the degeneracy between the complex mass
distribution of the lenses, substructures, the surface brightness distribution
of the sources, and the time delays. Using a novel inference framework based on
Approximate Bayesian Computation, we find that for all the considered lens
systems, an elliptical and cored power-law mass density distribution provides a
good fit to the data. However, the presence of cores in the simulated lenses
affects most reconstructions in the form of a Source Position Transformation.
The latter leads to a systematic underestimation of the source sizes by 50 per
cent on average, and a fractional error in of around
per cent. The analysis of a control sample of twenty-four lens systems, for
which we have perfect knowledge about the shape of the lensing potential, leads
to a fractional error on of per cent. We find no
degeneracy between complexity in the lensing potential and the inferred amount
of substructures. We recover an average total projected mass fraction in
substructures of at the 68 per cent
confidence level in agreement with zero and the fact that all substructures had
been removed from the simulation. Our work highlights the need for
higher-resolution simulations to quantify the lensing effect of more realistic
galactic potentials better, and that additional observational constraint may be
required to break existing degeneracies.Comment: Accepted by MNRA
Piezoelectric control of the magnetic anisotropy via interface strain coupling in a composite multiferroic structure
We investigate theoretically the magnetic dynamics in a
ferroelectric/ferromagnetic heterostructure coupled via strain-mediated
magnetoelectric interaction. We predict an electric field-induced magnetic
switching in the plane perpendicular to the magneto-crystalline easy axis, and
trace this effect back to the piezoelectric control of the magnetoelastic
coupling. We also investigate the magnetic remanence and the electric
coercivity
Biosurfactant production and surface translocation are regulated by PlcR in Bacillus cereus ATCC 14579 under low nutrient conditions
Bacillus cereus ATCC 14579 can respond to nutrient changes by adopting different forms of surface translocation. The B. cereus ATCC 14579 DeltaplcR mutant, but not the wild type, formed dendritic (branched) patterns on EPS [a low-nutrient medium that contains 7.0 g K(2)HPO(4), 3.0 g KH(2)PO(4), 0.1 g MgSO(4).7H(2)O, 0.1 g (NH(4))(2)SO(4), 0.01 g CaCl(2), 0.001 g FeSO(4), 0.1 g NaCl, 1.0 g glucose, and 125 mg yeast extract per liter] containing 0.7% agar. The dendritic patterns formed by sliding translocation of nonflagellated cells are enhanced under low-nutrient conditions and require sufficient production of a biosurfactant, which appears to be repressed by PlcR. The wild-type and complemented strains failed to slide on the surface of EPS agar because of the production of low levels of biosurfactant. Precoating EPS agar surfaces with surfactin (a biosurfactant produced by Bacillus subtilis) or biosurfactant purified from the DeltaplcR mutant rescued the ability of the wild-type and complemented strains to slide. When grown on a nutrient-rich medium like Luria-Bertani agar, both the wild-type and DeltaplcR mutant strains produced flagella. The wild type was hyperflagellated and elongated and exhibited swarming behavior, while the DeltaplcR mutant was multiflagellated and the cells often formed long chains but did not swarm. Thin-layer chromatography and mass spectrometry analyses suggested that the biosurfactant purified from the DeltaplcR mutant was a lipopeptide and had a mass of 1,278.1722 (m/z). This biosurfactant has hemolytic activity and inhibited the growth of several gram-positive bacteria
Systems-theoretic Safety Assessment of Robotic Telesurgical Systems
Robotic telesurgical systems are one of the most complex medical
cyber-physical systems on the market, and have been used in over 1.75 million
procedures during the last decade. Despite significant improvements in design
of robotic surgical systems through the years, there have been ongoing
occurrences of safety incidents during procedures that negatively impact
patients. This paper presents an approach for systems-theoretic safety
assessment of robotic telesurgical systems using software-implemented
fault-injection. We used a systemstheoretic hazard analysis technique (STPA) to
identify the potential safety hazard scenarios and their contributing causes in
RAVEN II robot, an open-source robotic surgical platform. We integrated the
robot control software with a softwareimplemented fault-injection engine which
measures the resilience of the system to the identified safety hazard scenarios
by automatically inserting faults into different parts of the robot control
software. Representative hazard scenarios from real robotic surgery incidents
reported to the U.S. Food and Drug Administration (FDA) MAUDE database were
used to demonstrate the feasibility of the proposed approach for safety-based
design of robotic telesurgical systems.Comment: Revise based on reviewers feedback. To appear in the the
International Conference on Computer Safety, Reliability, and Security
(SAFECOMP) 201
Stability of Solid State Reaction Fronts
We analyze the stability of a planar solid-solid interface at which a
chemical reaction occurs. Examples include oxidation, nitridation, or silicide
formation. Using a continuum model, including a general formula for the
stress-dependence of the reaction rate, we show that stress effects can render
a planar interface dynamically unstable with respect to perturbations of
intermediate wavelength
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