2,692 research outputs found
Relationship between pulse-wave velocity and arterial elasticity
Pulse wave velocity (PWV) was measured in situ in 11 isolated canine common carotid arteries. Seven arteries exhibited a linear PWV vs. pressure function at pressures ranging from 0 to 200 mmHg. Four arteries yielded a linear relationship between PWV and pressure between 1 and 100 mmHg; for these vessels the relationship was nonlinear at higher pressures. Seven arteries (five from the group which was linear up to 200 mmHg and two from the group which was linear up to 100 mmHg) were excised and pressure/volume measurements were made in vivo. Using pressure/volume data, the Moens-Korteweg equation was evaluated as a predictor of the PWV vs. pressure relationship over the linear region. An expression was developed to enable prediction of the pressure/volume relationship using the coefficients at the linear PWV vs. pressure function, and these predictions were evaluated. We found that, for this range, the Moens-Korteweg equation provides a very good basis for predicting the increase in PWV with increasing bias pressure. In addition, we found that the pressure/volume relationship of common carotid arteries is well represented by an exponential of the form V/V0 = Keαf(P) , which was derived as the inverse solution to the Moens-Korteweg equation
Field dependence of the vortex core size in a multi-band superconductor
The magnetic field dependence of the vortex core size in the multi-band
superconductor NbSe2 has been determined from muon spin rotation measurements.
The spatially extended nature of the quasiparticle core states associated with
the smaller gap leads to a rapid field-induced shrinkage of the core size at
low fields, while the more tightly bound nature of the states associated with
the larger gap leads to a field-independent core size for fields greater than 4
kOe. A simple model is proposed for the density of delocalized core states that
establishes a direct relationship between the field-induced reduction of the
vortex core size and the corresponding enhancement of the electronic thermal
conductivity. We show that this model accurately describes both NbSe2 and the
single-band superconductor V3Si.Comment: 4 pages, 4 figures. Version accepted for publication in Physical
Review Letter
Spin-glass state of vortices in YBa2Cu3Oy and La2-xSrxCuO4 below the metal-to-insulator crossover
Highly disordered magnetism confined to individual weakly interacting
vortices is detected by muon spin rotation in two different families of
high-transition-temperature superconductors, but only in samples on the
low-doping side of the low-temperature normal state metal-to-insulator
crossover (MIC). The results support an extended quantum phase transition (QPT)
theory of competing magnetic and superconducting orders that incorporates the
coupling between CuO2 planes. Contrary to what has been inferred from previous
experiments, the static magnetism that coexists with superconductivity near the
field-induced QPT is not ordered. Our findings unravel the mystery of the MIC
and establish that the normal state of high-temperature superconductors is
ubiquitously governed by a magnetic quantum critical point in the
superconducting phase.Comment: 9 pages, 9 figure
Structural properties of crumpled cream layers
The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy
Hole doping dependences of the magnetic penetration depth and vortex core size in YBa2Cu3Oy: Evidence for stripe correlations near 1/8 hole doping
We report on muon spin rotation measurements of the internal magnetic field
distribution n(B) in the vortex solid phase of YBa2Cu3Oy (YBCO) single
crystals, from which we have simultaneously determined the hole doping
dependences of the in-plane Ginzburg-Landau (GL) length scales in the
underdoped regime. We find that Tc has a sublinear dependence on
1/lambda_{ab}^2, where lambda_{ab} is the in-plane magnetic penetration depth
in the extrapolated limits T -> 0 and H -> 0. The power coefficient of the
sublinear dependence is close to that determined in severely underdoped YBCO
thin films, indicating that the same relationship between Tc and the superfluid
density is maintained throughout the underdoped regime. The in-plane GL
coherence length (vortex core size) is found to increase with decreasing hole
doping concentration, and exhibit a field dependence that is explained by
proximity-induced superconductivity on the CuO chains. Both the magnetic
penetration depth and the vortex core size are enhanced near 1/8 hole doping,
supporting the belief by some that stripe correlations are a universal property
of high-Tc cuprates.Comment: 12 pages, 13 figure
The effects of an eight over Cricket bowling spell upon pace bowling biomechanics and performance within different delivery lengths
Pace bowlers must often perform extended bowling spells with maximal ball release speed (BRS) while targeting different delivery lengths when playing a multi-day match. This study investigated the effect of an eight over spell upon pace bowling biomechanics and performance at different delivery lengths. Nine male bowlers (age = 18.8 ± 1.7 years) completed an eight over spell, while targeting different lengths (short: 7–10 m, good: 4–7 m, full: 0–4 m from the batter’s stumps, respectively) in a randomized order. Trunk, knee and shoulder kinematics and ground reaction forces at front foot contact (FFC), as well as run-up velocity and BRS were measured. Paired sample t-tests (p ≤ 0.01), Hedges’ g effect sizes, and statistical parametrical mapping were used to assess differences between mean variables from the first and last three overs. No significant differences (p = 0.05–0.98) were found in any discrete or continuous variables, with the magnitude of difference being trivial-to-medium (g = 0.00–0.73) across all variables. Results suggest pace bowlers sustain BRS through a single eight over spell while tolerating the repeatedly high whole-body biomechanical loads as suggested by maintaining the kinematics or technique at the assessed joints during FFC. Practically, the findings are advantageous for bowling performance and support current bowling load monitoring practices
EIT and diffusion of atomic coherence
We study experimentally the effect of diffusion of Rb atoms on
Electromagnetically Induced Transparency (EIT) in a buffer gas vapor cell. In
particular, we find that diffusion of atomic coherence in-and-out of the laser
beam plays a crucial role in determining the EIT resonance lineshape and the
stored light lifetime.Comment: 5 pages, 8 figure
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