617 research outputs found
Monte Carlo Simulation of Ising Models with Dipole Interaction
Recently, a new memory effect was found in the metamagnetic domain structure
of the diluted Ising antiferromagnet by domain imaging
with Faraday contrast. Essential for this effect is the dipole interaction. We
simulate the low temperature behavior of diluted Ising-antiferromagnets by a
Monte Carlo simulation considering long range interaction. The metamagnetic
domain structure occurring due to the dipole interaction is investigated by
graphical representation. In the model considered the antiferromagnetic state
is stable for an external magnetic field smaller than a lower boundary
while for fields larger than an upper boundary the system is in the
saturated paramagnetic phase, where the spins are ferromagnetically polarized.
For magnetic fields in between these two boundaries a mixed phase occurs
consisting of ferromagnetic domains in an antiferromagnetic background. The
position of these ferromagnetic domains is stored in the system: after a cycle
in which the field is first removed and afterwards applied again the domains
reappear at their original positions. The reason for this effect can be found
in the frozen antiferromagnetic domain state which occurs after removing the
field.Comment: Latex, 10 pages; 3 postsript-figures, compressed tar-file, uuencoded,
report 10109
Mechanical and dielectric relaxation spectra in seven highly viscous glass formers
Published dielectric and shear data of six molecular glass formers and one
polymer are evaluated in terms of a spectrum of thermally activated processes,
with the same barrier density for the retardation spectrum of shear and
dielectrics. The viscosity, an independent parameter of the fit, seems to be
related to the high-barrier cutoff time of the dielectric signal, in accordance
with the idea of a renewal of the relaxing entities after this critical time.
In the five cases where one can fit accurately, the temperature dependence of
the high-barrier cutoff follows the shoving model. The Johari-Goldstein peaks,
seen in four of our seven cases, are describable in terms of gaussians in the
barrier density, superimposed on the high-frequency tail of the
-process. Dielectric and shear measurements of the same substance find
the same peak positions and widths of these gaussians, but in general a
different weight.Comment: Contribution to the Ngai Fest issue of J. Non-Cryst. Solids; 8 pages,
8 figures, 30 reference
Advancing oral medicine through informatics and information technology: a proposed framework and strategy.
The implementation of information technology in healthcare is a significant focus for many nations around the world. However, information technology support for clinical care, research and education in oral medicine is currently poorly developed. This situation hampers our ability to transform oral medicine into a 'learning healthcare discipline' in which the divide between clinical practice and research is diminished and, ultimately, eliminated. This paper reviews the needs of and requirements for information technology support of oral medicine and proposes an agenda designed to meet those needs. For oral medicine, this agenda includes analyzing and reviewing current clinical and documentation practices, working toward progressively standardizing clinical data, and helping define requirements for oral medicine systems. IT professionals can contribute by conducting baseline studies about the use of electronic systems, helping develop controlled vocabularies and ontologies, and designing, implementing, and evaluating novel systems centered on the needs of clinicians, researchers and educators. Successfully advancing IT support for oral medicine will require close coordination and collaboration among oral medicine professionals, information technology professionals, system vendors, and funding agencies. If current barriers and obstacles are overcome, practice and research in oral medicine stand ready to derive significant benefits from the application of information technology
Effect of multilayer high-compression bandaging on ankle range of motion and oxygen cost of walking
Interference and zero-bias anomaly in tunneling between Luttinger-liquid wires
We present theoretical calculations and experimental measurements which
reveal the Luttinger-liquid (LL) nature of elementary excitations in a system
consisting of two quantum wires connected by a long narrow tunnel junction at
the edge of a GaAs/AlGaAs bilayer heterostructure. The boundaries of the wires
are important and lead to a characteristic interference pattern in measurements
on short junctions. We show that the experimentally observed modulation of the
conductance oscillation amplitude as a function of the voltage bias can be
accounted for by spin-charge separation of the elementary excitations in the
interacting wires. Furthermore, boundaries affect the LL exponents of the
voltage and temperature dependence of the tunneling conductance at low
energies. We show that the measured temperature dependence of the conductance
zero-bias dip as well as the voltage modulation of the conductance oscillation
pattern can be used to extract the electron interaction parameters in the
wires.Comment: 17 pages, 12 figure
Quantum-mechanical calculation of H on Ni(001) using a model potential based on first-principles calculations
Association of Plasma Neurofilament Light With Neurodegeneration in Patients With Alzheimer Disease
IMPORTANCE: Existing cerebrospinal fluid (CSF) or imaging (tau positron emission tomography) biomarkers for Alzheimer disease (AD) are invasive or expensive. Biomarkers based on standard blood test results would be useful in research, drug development, and clinical practice. Plasma neurofilament light (NFL) has recently been proposed as a blood-based biomarker for neurodegeneration in dementias. OBJECTIVE: To test whether plasma NFL concentrations are increased in AD and associated with cognitive decline, other AD biomarkers, and imaging evidence of neurodegeneration. DESIGN, SETTING, AND PARTICIPANTS: In this prospective case-control study, an ultrasensitive assay was used to measure plasma NFL concentration in 193 cognitively healthy controls, 197 patients with mild cognitive impairment (MCI), and 180 patients with AD dementia from the Alzheimer's Disease Neuroimaging Initiative. The study dates were September 7, 2005, to February 13, 2012. The plasma NFL analysis was performed in September 2016. MAIN OUTCOMES AND MEASURES: Associations were tested between plasma NFL and diagnosis, Aβ pathologic features, CSF biomarkers of neuronal injury, cognition, brain structure, and metabolism. RESULTS: Among 193 cognitively healthy controls, 197 patients with mild cognitive impairment, and 180 patients with AD with dementia, plasma NFL correlated with CSF NFL (Spearman ρ = 0.59, P < .001). Plasma NFL was increased in patients with MCI (mean, 42.8 ng/L) and patients with AD dementia (mean, 51.0 ng/L) compared with controls (mean, 34.7 ng/L) (P < .001) and had high diagnostic accuracy for patients with AD with dementia vs controls (area under the receiver operating characteristic curve, 0.87, which is comparable to established CSF biomarkers). Plasma NFL was particularly high in patients with MCI and patients with AD dementia with Aβ pathologic features. High plasma NFL correlated with poor cognition and AD-related atrophy (at baseline and longitudinally) and with brain hypometabolism (longitudinally). CONCLUSIONS AND RELEVANCE: Plasma NFL is associated with AD diagnosis and with cognitive, biochemical, and imaging hallmarks of the disease. This finding implies a potential usefulness for plasma NFL as a noninvasive biomarker in AD
Leaf venation, as a resistor, to optimize a switchable IR absorber
Leaf vascular patterns are the mechanisms and mechanical support for the transportation of fluidics for photosynthesis and leaf development properties. Vascular hierarchical networks in leaves have far-reaching functions in optimal transport efficiency of functional fluidics. Embedding leaf morphogenesis as a resistor network is significant in the optimization of a translucent thermally functional material. This will enable regulation through pressure equalization by diminishing flow pressure variation. This paper investigates nature’s vasculature networks that exhibit hierarchical branching scaling applied to microfluidics. To enable optimum potential for pressure drop regulation by algorithm design. This code analysis of circuit conduit optimization for transport fluidic flow resistance is validated against CFD simulation, within a closed loop network. The paper will propose this self-optimization, characterization by resistance seeking targeting to determine a microfluidic network as a resistor. To advance a thermally function material as a switchable IR absorber
Dust depletion of of metals from local to distant galaxies II: Cosmic dust-to-metal ratio and dust composition
The evolution of the cosmic dust content and the cycle between metals and
dust in the interstellar medium (ISM) play a fundamental role in galaxy
evolution. The chemical enrichment of the Universe can be traced through the
evolution of the dust-to-metals ratio (DTM) and the dust-to-gas ratio (DTG)
with metallicity. We use a novel method to determine mass estimates of the DTM,
DTG and dust composition based on our previous measurements of the depletion of
metals in different environments (the Milky Way, the Magellanic Clouds, and
damped Lyman- absorbers, DLAs, toward quasars and towards gamma-ray
bursts, GRBs), which were calculated from the relative abundances of metals in
the ISM through absorption-line spectroscopy column densities observed mainly
from VLT/UVES and X-shooter, and HST/STIS. We derive the dust extinction from
the estimated dust depletion () and compare with the
from extinction. We find that the DTM and DTG ratios increase with metallicity
and with the dust tracer [Zn/Fe]. This suggests that grain growth in the ISM is
a dominant process of dust production. The increasing trend of the DTM and DTG
with metallicity is in good agreement with a dust production and evolution
model. Our data suggest that the stellar dust yield is much lower than the
metal yield and thus that the overall amount of dust in the warm neutral medium
that is produced by stars is much lower. We find that is
overall lower than for the Milky Way and a few Magellanic
Clouds lines of sight, a discrepancy that is likely related to the presence of
carbonaceous dust. We show that the main elements that contribute to the dust
composition are, O, Fe, Si, Mg, C, S, Ni and Al for all the environments.
Abundances at low dust regimes suggest the presence of pyroxene and metallic
iron in dust.Comment: Accepted for publication in A&A. Abstract abridge
Performance of Fully Automated Plasma Assays as Screening Tests for Alzheimer Disease-Related β-Amyloid Status
Importance: Accurate blood-based biomarkers for Alzheimer disease (AD) might improve the diagnostic accuracy in primary care, referrals to memory clinics, and screenings for AD trials. //
Objective: To examine the accuracy of plasma β-amyloid (Aβ) and tau measured using fully automated assays together with other blood-based biomarkers to detect cerebral Aβ. //
Design, Setting, and Participants: Two prospective, cross-sectional, multicenter studies. Study participants were consecutively enrolled between July 6, 2009, and February 11, 2015 (cohort 1), and between January 29, 2000, and October 11, 2006 (cohort 2). Data were analyzed in 2018. The first cohort comprised 842 participants (513 cognitively unimpaired [CU], 265 with mild cognitive impairment [MCI], and 64 with AD dementia) from the Swedish BioFINDER study. The validation cohort comprised 237 participants (34 CU, 109 MCI, and 94 AD dementia) from a German biomarker study. //
Main Outcome and Measures: The cerebrospinal fluid (CSF) Aβ42/Aβ40 ratio was used as the reference standard for brain Aβ status. Plasma Aβ42, Aβ40 and tau were measured using Elecsys immunoassays (Roche Diagnostics) and examined as predictors of Aβ status in logistic regression models in cohort 1 and replicated in cohort 2. Plasma neurofilament light chain (NFL) and heavy chain (NFH) and APOE genotype were also examined in cohort 1. //
Results: The mean (SD) age of the 842 participants in cohort 1 was 72 (5.6) years, with a range of 59 to 88 years, and 446 (52.5%) were female. For the 237 in cohort 2, mean (SD) age was 66 (10) years with a range of 23 to 85 years, and 120 (50.6%) were female. In cohort 1, plasma Aβ42 and Aβ40 predicted Aβ status with an area under the receiver operating characteristic curve (AUC) of 0.80 (95% CI, 0.77-0.83). When adding APOE, the AUC increased significantly to 0.85 (95% CI, 0.82-0.88). Slight improvements were seen when adding plasma tau (AUC, 0.86; 95% CI, 0.83-0.88) or tau and NFL (AUC, 0.87; 95% CI, 0.84-0.89) to Aβ42, Aβ40 and APOE. The results were similar in CU and cognitively impaired participants, and in younger and older participants. Applying the plasma Aβ42 and Aβ40 model from cohort 1 in cohort 2 resulted in slightly higher AUC (0.86; 95% CI, 0.81-0.91), but plasma tau did not contribute. Using plasma Aβ42, Aβ40, and APOE in an AD trial screening scenario reduced positron emission tomography costs up to 30% to 50% depending on cutoff. //
Conclusions and Relevance: Plasma Aβ42 and Aβ40 measured using Elecsys immunoassays predict Aβ status in all stages of AD with similar accuracy in a validation cohort. Their accuracy can be further increased by analyzing APOE genotype. Potential future applications of these blood tests include prescreening of Aβ positivity in clinical AD trials to lower the costs and number of positron emission tomography scans or lumbar punctures
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