2,349 research outputs found
Constrained motions and slow dynamics in one-dimensional bosons with double-well dispersion
We investigate the dynamical properties of one-dimensional interacting bosons
with double-well dispersion, which can be realized in the ultracold atom
experiments. We demonstrate slow dynamics and constrained motion of domain
walls in the low-temperature symmetry-broken regime. The constrained
domain-wall motion is ``fracton-like'' -- a single domain wall cannot move
freely, while two nearby domain walls can move collectively. Such an unusual
property stems from the emergent dipole moment conservation in the
symmetry-broken regime. Consequently, we find an Ohmic-like linear response and
a vanishing superfluid stiffness, which are atypical for gases in a
disorder-free background in one dimension - but similar to a 2D superfluid with
free vortices. In addition, we develop a hydrodynamic description for the
dynamics controlled by the interacting quantum Lifshitz critical point and
obtain superfluid stiffness and sound velocity , showing qualitatively similar low-temperature dynamics to the
symmetry-broken regime. Our results reveal several unprecedented dynamical
properties relevant to the fractons and explain the stable domain walls in the
existing experiments.Comment: 21 pages, 4 figure
The neuroprotective actions of perinatal choline supplementation on amyloidosis in APP.NLGF knock-in Alzheimer's disease model mice
Alzheimer’s Disease is a growing public health problem, with the number of Americans suffering from the disease projected to more than double from 5.8 million today to 13.8 million in 2050. While there is still no cure for Alzheimer’s Disease, a preventative strategy may mitigate its cost to society in the future. Previous studies have shown an ameliorative effect of perinatal choline supplementation on amyloidosis in the hippocampus of APP.PS1 mice. In this study, we test the effects of perinatal choline supplementation on the APP.NLGF strain of mice – which uses a gene knock-in strategy to avoid the non-physiologic overexpression of amyloid precursor protein and better recapitulate the disease in humans. When compared to APP.NLGF mice raised on a control diet, the perinatal choline supplemented APP.NLGF mice exhibited: i) an amelioration of learning and memory deficits in 9- and 12-months old mice as measured by contextual fear conditioning, ii) reduced amyloidosis in the cortex of 9- and 12-months old mice, and iii) an age- and brain region-dependent response to perinatal choline supplementation. These results suggest that increasing the dietary intake of choline during pregnancy may protect the offspring from AD-associated cognitive decline and amyloidosis
Sustainable development or the resource curse? : the role of CSR at Newmont’s Ahafo Mine in Ghana
ii, 137 leaves ; 29 cm.Includes abstract and appendices.Includes bibliographical references (leaves 115-130).Corporate Social Responsibility claims that social and economic development is possible in mineral-dependent countries. Viewed as a tool for reducing impacts of mining, CSR is increasingly implemented on a voluntary basis by mining companies. Such claims assume that mining and development can be achieved, and that through CSR, resource rich countries can avoid negative impacts of resource development, also
known as the “resource curse”. This thesis seeks to explore CSR’s attempts to address some of the factors that limit’s mining’s contributions to development. In examining Newmont Mining Corporation’s Ahafo Mine in Ghana, the research finds that CSR seeks to mitigate the economic, social, and political impacts of mining. Specifically, voluntary CSR promotes local economic development, human development in areas of education and health, and improve transparency and accountability. However, the research finds that without government involvement, CSR is ineffective due to voluntary nature of the programs
Acoustic-phonon-mediated superconductivity in moir\'eless graphene multilayers
We investigate the competition between acoustic-phonon-mediated
superconductivity and the long-range Coulomb interaction in moir\'eless
graphene multilayers, specifically, Bernal bilayer graphene, rhombohedral
trilayer graphene, and ABCA-stacked tetralayer graphene. In these graphene
multilayers, the acoustic phonons can realize, through electron-phonon
coupling, both spin-singlet and spin-triplet pairings, and the intra-sublattice
pairings (-wave spin-singlet and -wave spin-triplet) are the dominant
channels. Our theory naturally explains the distinct recent experimental
findings in Bernal bilayer graphene and rhombohedral trilayer graphene, and we
further predict existence of superconductivity in ABCA tetralayer graphene
arising from electron-phonon interactions. In particular, we demonstrate that
the acoustic-phonon-mediated superconductivity prevails over a wide range of
doping in rhombohedral trilayer graphene and ABCA tetralayer graphene while
superconductivity exists only in a narrow range of doping near the Van Hove
singularity in Bernal bilayer graphene. Key features of our theory are the
inclusion of realistic band structures with the appropriate Van Hove
singularities and Coulomb repulsion effects (the so-called " effect")
opposing the phonon-induced superconducting pairing. We also discuss how
intervalley scatterings can suppress the spin-triplet spin-polarized
superconductivity. Our work provides detailed prediction based on
electron-acoustic-phonon-interaction-induced graphene superconductivity, which
should be investigated in future experiments.Comment: 19 pages, 13 figure
An evaluation of personal cooling systems for reducing thermal strain whilst working in chemical/biological protective clothing
© 2019 The Authors. Published by Frontiers Media. This is an open access article available under a Creative Commons licence.
The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3389/fphys.2019.00424© 2019 Bach, Maley, Minett, Zietek, Stewart and Stewart. Objective: The use of personal cooling systems to mitigate heat strain on first-responders achieves two potential performance benefits relative to the absence of such cooling: (1) the completion of a workload with less effort; and/or (2) the completion of a greater workload for the same effort. Currently, claims made by manufacturers regarding the capability of their products for use in conjunction with chemical/biological protective clothing remain largely unsubstantiated. The purpose of this investigation was to evaluate the means by which heat strain can be alleviated during uncompensable heat stress in chemical/biological clothing, using the ASTM F2300-10 methodology. Methods: Eight healthy males completed five trials of continuous walking (4.5 km h-1; 35°C; 49% RH) for up to 120 min while wearing one of four cooling systems and/or a National Fire and Protection Association 1994 Class-3 chemical/biological ensemble. The four cooling methods (ice vest [IV], phase-change vest [PCM], water-perfused suit [WS], and combination ice slurry/ice vest [SLIV]) and no cooling (CON). Results: We observed significant improvements in trial times for IV (18 ± 10 min), PCM (20 ± 10 min) and SLIV (22 ± 10 min), but no differences for WS (4 ± 7 min). Heart rate, rectal, mean skin, and body temperatures were significantly lower in all cooling conditions relative to control at various matched time points in the first 60 min of exercise. Thermal sensation, comfort and perceived exertion all had significant main effects for condition, and time, there were no differences in their respective interactions. Conclusion: The IV, PCM, and SLIV produced lower heart rate, mean skin, rectal and mean body temperatures in addition to improved work times compared to control. The WS did not improve work times possibly as a result of the cooling capacity of the suit abating, and magnifying thermal insulation. Considering the added time and resources required to implement combination cooling in the form of ice slurry and ice vest (SLIV), there was no significant additive effect for perception, cardiovascular strain, rectal temperature and total trial time relative to the phase change vest or ice vest alone. This may be a product of a "ceiling" effect for work limit set to 120 min as part of ASTM F2300-10.This project is financially supported by the United States Government through the United States Department of Defense (DOD).Published versio
7-Hydroxyindan-1-one
In the title compound, C9H8O2, an intramolecular O—H⋯O hydrogen bond generates an S(6) ring. The dihedral angle between the mean plane of the S(6) ring and the benzene ring is 1.89 (2)°. In the crystal, inversion-related molecules are linked by pairs of O—H⋯O hydrogen bonds, forming a cyclic dimers with R
2
2(12) graph-set motif. Weak intermolecular C—H⋯Ocarbonyl and C—H⋯Ohydroxy hydrogen bonds link the dimers into chains along [010], generating two C(6) motifs that overlap three C atoms, forming R
2
2(8) ring motifs
The ACS Survey of Galactic Globular Clusters XI: The Three-Dimensional Orientation of the Sagittarius Dwarf Spheroidal Galaxy and its Globular Clusters
We use observations from the ACS study of Galactic globular clusters to
investigate the spatial distribution of the inner regions of the disrupting
Sagittarius dwarf spheroidal galaxy (Sgr). We combine previously published
analyses of four Sgr member clusters located near or in the Sgr core (M54, Arp
2, Terzan 7 and Terzan 8) with a new analysis of diffuse Sgr material
identified in the background of five low-latitude Galactic bulge clusters (NGC
6624, 6637, 6652, 6681 and 6809) observed as part of the ACS survey. By
comparing the bulge cluster CMDs to our previous analysis of the M54/Sgr core,
we estimate distances to these background features. The combined data from four
Sgr member clusters and five Sgr background features provides nine independent
measures of the Sgr distance and, as a group, provide uniformly measured and
calibrated probes of different parts of the inner regions of Sgr spanning
twenty degrees over the face of the disrupting dwarf. This allows us, for the
first time, to constrain the three dimensional orientation of Sgr's disrupting
core and globular cluster system and compare that orientation to the
predictions of an N-body model of tidal disruption. The density and distance of
Sgr debris is consistent with models that favor a relatively high Sgr core mass
and a slightly greater distance (28-30 kpc, with a mean of 29.4 kpc). Our
analysis also suggests that M54 is in the foreground of Sgr by ~2 kpc,
projected on the center of the Sgr dSph. While this would imply a remarkable
alignment of the cluster and the Sgr nucleus along the line of sight, we can
not identify any systematic effect in our analysis that would falsely create
the measured 2 kpc separation. Finally, we find that the cluster Terzan 7 has
the most discrepant distance (25 kpc) among the four Sgr core clusters, which
may suggest a different dynamical history than the other Sgr core clusters.Comment: 41 pages, 16 figures, accepted to Ap
Angiographically silent atherosclerosis detected by intravascular ultrasound in patients with familial hypercholesterolemia and familial combined hyperlipidemia: Correlation with high density lipoproteins
AbstractObjectives. This study sought to evaluate the extent of atherosclerosis in coronary and iliac arteries in patients with heterozygous familial hypercholesterolemia or familial combined hyperlipidemia, using intravascular ultraound imaging.Background. Intravascular ultrasound imaging provides cross-sectional tomographic views of the vessel wall and allows quantitative assessment of atherosclerosis.Methods. Forty-eight nonsmoking, asymptomatic patients with heterozygous familial hypercholesterolemia or familial combined hyperlipidemia underwent intravascular ultrasound imaging of the left anterior descending coronary, left main coronary and common iliac arteries. Angiography showed only minimal or no narrowing in these vessels. Intravascular ultrasound images obtained during catheter pullback underwent morphometric analysis. Plaque burden was expressed as the mean and maximal intimal index (ratio of plaque area and area within the internal elastic lamina) and as the percent of vessel surface covered by plaque.Results. Intravascular ultrasound detected plaque more frequently than angiography in the left anterior descending (80% vs. 29%, respectively), left main (44% vs. 16%) and iliac arteries (33% vs. 27%). Plaque burden was higher in the left anterior descending (mean intimal index [±SD] 0.25 ± 0.16) than in the left main (0.11 ± 0.16, p < 0.001) and iliac arteries (0.02 ± 0.04, p < 0.001). Angiography detected lumen narrowing only in coronary arteries with a maximal intimal index ⪰0.42 (left anterior descending artery) and ⪰0.43 (left main artery). The area within the internal elastic lamina increased with plaque area in the left anterior descending (r = 0.82, p < 0.001) and left main arteries (r = 0.53, p < 0.001). By stepwise multiple regression analysis, the strongest predictor for plaque burden in the left anterior descending artery was the level of high density lipoprotein (HDL) cholesterol and total/HDL cholesterol ratio for the left main artery.Conclusions. In patients with heterozygous familial hypercholesterolemia and familial combined hyperlipidemia, extensive coronary plaque is present despite minimal or no angiographic changes. Compensatory vessel enlargement and diffuse involvement with eccentric plaque may account for the lack of angiographic changes. Levels of HDL cholesterol and total/HDL cholesterol ratio are far more powerful predictors of coronary plaque burden than are low density lipoprotein cholesterol levels in these patients with early, asymptomatic disease
Development of the Roll Type Incremental Micro Pattern Imprint System for Large Area Pattern Replication
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