8,374 research outputs found
Effect of hydrophobic solutes on the liquid-liquid critical point
Jagla ramp particles, interacting through a ramp potential with two
characteristic length scales, are known to show in their bulk phase
thermodynamic and dynamic anomalies, similar to what is found in water. Jagla
particles also exhibit a line of phase transitions separating a low density
liquid phase and a high density liquid phase, terminating in a liquid-liquid
critical point in a region of the phase diagram that can be studied by
simulations. Employing molecular dynamics computer simulations, we study the
thermodynamics and the dynamics of solutions of hard spheres (HS) in a solvent
formed by Jagla ramp particles. We consider the cases of HS mole fraction x =
0.10, 0.15 and 0.20, and also the case x = 0.50 (a 1:1 mixture of HS and Jagla
particles). We find a liquid-liquid critical point, up to the highest HS mole
fraction; its position shifts to higher pressures and lower temperatures upon
increasing x. We also find that the diffusion coefficient anomalies appear to
be preserved for all the mole fractions studied.Comment: 8 pages, 7 figures, 1 table. In press (Phys. Rev. E
Three-Dimensional Percolation Modeling of Self-Healing Composites
We study the self-healing process of materials with embedded "glue"-carrying
cells, in the regime of the onset of the initial fatigue. Three-dimensional
numerical simulations within the percolation-model approach are reported. The
main numerical challenge taken up in the present work, has been to extend the
calculation of the conductance to three-dimensional lattices. Our results
confirm the general features of the process: The onset of the material fatigue
is delayed, by developing a plateau-like time-dependence of the material
quality. We demonstrate that in this low-damage regime, the changes in the
conductance and thus, in similar transport/response properties of the material
can be used as measures of the material quality degradation. A new feature
found for three dimensions, where it is much more profound than in
earlier-studied two-dimensional systems, is the competition between the healing
cells. Even for low initial densities of the healing cells, they interfere with
each other and reduce each other's effective healing efficiency.Comment: 15 pages in PDF, with 6 figure
Millisecond spin-flip times of donor-bound electrons in GaAs
We observe millisecond spin-flip relaxation times of donor-bound electrons in
high-purity n-GaAs . This is three orders of magnitude larger than previously
reported lifetimes in n-GaAs . Spin-flip times are measured as a function of
magnetic field and exhibit a strong power-law dependence for fields greater
than 4 T . This result is in qualitative agreement with previously reported
theory and measurements of electrons in quantum dots.Comment: 4 pages, 4 figure
Electronic Phase Separation Transition as the Origin of the Superconductivity and the Pseudogap Phase of Cuprates
We propose a new phase of matter, an electronic phase separation transition
that starts near the upper pseudogap and segregates the holes into high and low
density domains. The Cahn-Hilliard approach is used to follow quantitatively
this second order transition. The resulting grain boundary potential confines
the charge in domains and favors the development of intragrain superconducting
amplitudes. The zero resistivity transition arises only when the intergrain
Josephson coupling is of the order of the thermal energy and phase
locking among the superconducting grains takes place. We show that this
approach explains the pseudogap and superconducting phases in a natural way and
reproduces some recent scanning tunneling microscopy dataComment: 4 pages and 5 eps fig
Experimental Characterisation of GLass Aluminum REinforced (GLARE™) laminates
Fibre metal laminates such as GLARE™ have found promising application in the aerospace industry. These laminates were developed at the structures and materials laboratory of Delft University of Technology, Netherlands. GLARE™ is a material belonging to the family of Fibre Metal Laminates consisting of thin aluminum layers bonded with unidirectional S2-Glass fibres with an adhesive. Aluminum and S2-Glass when combined as a hybrid material can provide best features of the both metals and composites. These materials have excellent fatigue, impact and damage tolerance characteristics and a lower density compared to aluminum. GLARE™ has found major application in front and aft upper fuselage, leading edges of empennages of advanced civil aircrafts like A380. This document looks into the evaluation of two configuration of GLARE™ for its mechanical and impact characteristics. The mechanical characterisation was carried out for tensile, compression, Flexure, ILSS, Open Hole Tension, Open Hole Compression and Shear (Iosipescu). The impact behaviour were characterised based on a low velocity drop weight impact carried on these laminates. The study shows that the basic properties evaluated were more dictated by the property of the S2-Glass used. The studies show that GLARE™ laminates posses’ high impact damage resistance compared to other composite material. All the test datas generated for this study will be brought out in this document
On the distribution of career longevity and the evolution of home run prowess in professional baseball
Statistical analysis is a major aspect of baseball, from player averages to
historical benchmarks and records. Much of baseball fanfare is based around
players exceeding the norm, some in a single game and others over a long
career. Career statistics serve as a metric for classifying players and
establishing their historical legacy. However, the concept of records and
benchmarks assumes that the level of competition in baseball is stationary in
time. Here we show that power-law probability density functions, a hallmark of
many complex systems that are driven by competition, govern career longevity in
baseball. We also find similar power laws in the density functions of all major
performance metrics for pitchers and batters. The use of performance-enhancing
drugs has a dark history, emerging as a problem for both amateur and
professional sports. We find statistical evidence consistent with
performance-enhancing drugs in the analysis of home runs hit by players in the
last 25 years. This is corroborated by the findings of the Mitchell Report [1],
a two-year investigation into the use of illegal steroids in major league
baseball, which recently revealed that over 5 percent of major league baseball
players tested positive for performance-enhancing drugs in an anonymous 2003
survey.Comment: 5 pages, 5 figures, 2-column revtex4 format. Revision has change of
title, a figure added, and minor changes in response to referee comment
Single Transverse-Spin Asymmetries at Large-x
The large- behavior of the transverse-momentum dependent quark
distributions is analyzed in the factorization-inspired perturbative QCD
framework, particularly for the naive time-reversal-odd quark Sivers function
which is responsible for the single transverse-spin asymmetries in various
semi-inclusive hard processes. By examining the dominant hard gluon exchange
Feynman diagrams, and using the resulting power counting rule, we find that the
Sivers function has power behavior at , which is one power
of suppressed relative to the unpolarized quark distribution. These
power-counting results provide important guidelines for the parameterization of
quark distributions and quark-gluon correlations.Comment: 20 pages, 4 figure
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