2,012 research outputs found
An investigation into the damage development and residual strengths of open-hole specimens in fatigue
Probing short-range magnetic order in a geometrically frustrated magnet by spin Seebeck effect
Competing magnetic interactions in geometrically frustrated magnets give rise
to new forms of correlated matter, such as spin liquids and spin ices.
Characterizing the magnetic structure of these states has been difficult due to
the absence of long-range order. Here, we demonstrate that the spin Seebeck
effect (SSE) is a sensitive probe of magnetic short-range order (SRO) in
geometrically frustrated magnets. In low temperature (2 - 5 K) SSE measurements
on a model frustrated magnet \mathrm{Gd_{3}Ga_{5}O_{12}}, we observe
modulations in the spin current on top of a smooth background. By comparing to
existing neutron diffraction data, we find that these modulations arise from
field-induced magnetic ordering that is short-range in nature. The observed SRO
is anisotropic with the direction of applied field, which is verified by
theoretical calculation.Comment: 5 pages, 4 figure
Principal Component Analysis with Noisy and/or Missing Data
We present a method for performing Principal Component Analysis (PCA) on
noisy datasets with missing values. Estimates of the measurement error are used
to weight the input data such that compared to classic PCA, the resulting
eigenvectors are more sensitive to the true underlying signal variations rather
than being pulled by heteroskedastic measurement noise. Missing data is simply
the limiting case of weight=0. The underlying algorithm is a noise weighted
Expectation Maximization (EM) PCA, which has additional benefits of
implementation speed and flexibility for smoothing eigenvectors to reduce the
noise contribution. We present applications of this method on simulated data
and QSO spectra from the Sloan Digital Sky Survey.Comment: Accepted for publication in PASP; v2 with minor updates, mostly to
bibliograph
Effect of acute tensile loading on gender-specific tendon structural and mechanical properties.
Stretching is commonly used prior to exercise, as it is thought to reduce the risk of injury, and it is also used in the preconditioning of tendon grafts. As tendon properties have been shown to be different between genders, it is proposed that stretching will differentially affect the structure. Here we examine the effect of acute stretch on the mechanical properties of both male and female medial gastrocnemius tendon. Female [20 years ± 1 (SEM), n = 17] and male (22 years ±1, n = 18) subjects underwent a 5-min passive dorsiflexion stretch. Prior to and post stretch medial gastrocnemius tendon stiffness (K), length (1) and cross-sectional area (csa) were measured using ultrasonography and dynamometry. Stiffness and Young's modulus (ε) were significantly reduced with stretch for both genders (p < 0.05). Females showed significantly (p < 0.05) greater pre- to poststretch decreases in K (22.4 vs. 8, 8%) and e (20.5 vs. 8.4%) in comparison to males. The present results show that stretching acutely reduces stiffness of the medial gastrocnemius tendon in females and males, with females showing significantly greater change. The observed disparity between genders may be due in part to variations in tendon moment arm and intrinsic differences in tendon composition. These differential changes in tendon mechanical properties have functional, motor control, and injury risk implications, as well as possible implications for preconditioning of tendon grafts
Antiferromagnetic spin Seebeck Effect
We report on the observation of the spin Seebeck effect in antiferromagnetic
MnF. A device scale on-chip heater is deposited on a bilayer of Pt (4
nm)/MnF (110) (30 nm) grown by molecular beam epitaxy on a MgF (110)
substrate. Using Pt as a spin detector layer it is possible to measure
thermally generated spin current from MnF through the inverse spin Hall
effect. The low temperature (2 - 80 K) and high magnetic field (up to 140 kOe)
regime is explored. A clear spin flop transition corresponding to the sudden
rotation of antiferromagnetic spins out of the easy axis is observed in the
spin Seebeck signal when large magnetic fields (>9 T) are applied parallel the
easy axis of the MnF thin film. When magnetic field is applied
perpendicular to the easy axis, the spin flop transition is absent, as
expected
Quantitative MRI evaluation of whole abdomen adipose tissue volumes in healthy volunteers-validation of technique and implications for clinical studies
A Novel Hyper-Viscoelastic Model for Consolidation of Toughened Prepregs under Processing Conditions
Chromatin profiling of Drosophila CNS subpopulations identifies active transcriptional enhancers
One of the key issues in studying transcriptional regulation during development is how to employ genome-wide assays that reveals sites of open chromatin and transcription factor binding to efficiently identify biologically relevant genes and enhancers. Analysis of Drosophila CNS midline cell development provides a useful system for studying transcriptional regulation at the genomic level due to a large, well-characterized set of midline-expressed genes and in vivo validated enhancers. In this study, FAIRE-seq on FACS-purified midline cells was performed and the midline FAIRE data were compared with whole-embryo FAIRE data. We find that regions of the genome with a strong midline FAIRE peak and weak whole-embryo FAIRE peak overlap with known midline enhancers and provide a useful predictive tool for enhancer identification. In a complementary analysis, we compared a large dataset of fragments that drive midline expression in vivo with the FAIRE data. Midline enhancer fragments with a midline FAIRE peak tend to be near midline-expressed genes, whereas midline enhancers without a midline FAIRE peak were often distant from midline-expressed genes and unlikely to drive midline transcription in vivo
The Western Australian Aboriginal Child Health Survey: Strengthening the Capacity of Aboriginal Children, Families and Communities.
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