2,913 research outputs found
Combustion of the butanol isomers: reaction pathways at elevated pressures from low-to-high temperatures
The Gould-Hopper Polynomials in the Novikov-Veselov equation
We use the Gould-Hopper (GH) polynomials to investigate the Novikov-Veselov
(NV) equation. The root dynamics of the -flow in the NV equation is
studied using the GH polynomials and then the Lax pair is found. In particulr,
when , one can get the Gold-fish model. The smooth rational solutions
of the NV equation are also constructed via the extended Moutard transformation
and the GH polynomials. The asymptotic behavior is discussed and then the
smooth rational solution of the Liouville equation is obtained.Comment: 22 pages, no figur
High-temperature integrated and flexible ultrasonic transducers for nondestructive testing
Integrated ultrasonic transducers (IUTs) and flexible ultrasonic transducers (FUTs) are presented for nondestructive testing at high temperatures. These transducers are made of sol-gel-sprayed piezoelectric thick (>40 \ub5m) ceramic films. The ceramic materials are lead-zirconate-titanate, bismuth titanate and lithium niobate which are for thickness measurements up to 150, 400 and 800\ub0C, respectively. The IUT can also be deposited onto one end of a long ultrasonic delay line to perform nondestructive testing at the other end at even higher temperatures. FUTs made of bismuth titanate films onto thin stainless steel foils are also used for thickness measurements at 300\ub0C with a high-temperature couplant sandwiched between the FUT and a steel substrate. All experiments at high temperatures were performed in pulse-echo mode and ultrasonic echoes with signal-to-noise ratios above 20 dB were obtained. The center operation frequencies of both IUTs and FUTs range from 4.4 to 10.7 MHz.On pr\ue9sente des transducteurs ultrasoniques int\ue9gr\ue9s (TUI) et des transducteurs ultrasoniques souples (TUS) \ue0 des fins d\u2019essai \ue0 haute temp\ue9rature. Ces transducteurs sont en films c\ue9ramiques \ue9pais (> 40 \u3bcm), pi\ue9zo\ue9lectriques de type sol-gel pulv\ue9ris\ue9. Au nombre des mat\ue9riaux c\ue9ramiques figurent le titanate, le zirconate de plomb, le titanate de bismuth et le niobate de lithium; mat\ue9riaux qui conviennent pour des mesures d\u2019\ue9paisseur jusqu\u2019\ue0 150, 400 et 800 \ub0C respectivement. Les TUI peuvent aussi \ueatre d\ue9pos\ue9s \ue0 une extr\ue9mit\ue9 d\u2019une longue ligne de retard ultrasonique pour r\ue9aliser un essai non destructif \ue0 l\u2019autre extr\ue9mit\ue9 \ue0 des temp\ue9ratures encore plus \ue9lev\ue9es. Les TUS en film de titanate de bismuth sur de fines feuilles d\u2019acier inoxydable sont \ue9galement utilis\ue9s pour des mesures d\u2019\ue9paisseur \ue0 300 \ub0C avec un agent couplant pris en sandwich entre le TUS et un substrat en acier. Toutes les exp\ue9riences \ue0 haute temp\ue9rature ont \ue9t\ue9 r\ue9alis\ue9es en mode impulsion/\ue9cho, et on a obtenu des \ue9chos ultrasoniques avec des rapports signal/bruit sup\ue9rieurs \ue0 20 dB. Les fr\ue9quences centrales d\u2019exploitation des TUI et des TUS \ue9taient situ\ue9es dans la gamme allant de 4,4 \ue0 10,7 MHz.Peer reviewed: YesNRC publication: Ye
Connected-Sea Partons
According to the path-integral formalism of the hadronic tensor, the nucleon
sea contains two distinct components called connected sea (CS) and disconnected
sea (DS). We discuss how the CS and DS are accessed in the lattice QCD
calculation of the moments of the parton distributions. We show that the CS and
DS components for can be extracted by using recent data
on the strangeness parton distribution, the CT10 global fit, and the lattice
result of the ratio of the strange to moments in the disconnected
insertion. The extracted CS and DS for have distinct
Bjorken dependence in qualitative agreement with expectation. The analysis
also shows that the momentum fraction of the is about
equally divided between CS and DS at . Implications on
future global analysis for parton distributions are presented.Comment: Revised version to be published in Phys. Rev. Let
Characterization of cladded glass fibers using acoustic microscopy
Spatial distribution profiles of leaky surface acoustic wave velocity V(LSAW) and attenuation across the diameters of cladded glass fibers are presented. The profiles are obtained by using a novel V(x,z) analysis with a reflection scanning acoustic microscope operated at 775 MHz, and are compared with optical refractive index profiles. Optical fibers with different dopants and dopant concentrations have been investigated. The role of acoustic property profiles in the design of optical and acoustic fibers is outlined
Spin Relaxation in Single Layer Graphene with Tunable Mobility
Graphene is an attractive material for spintronics due to theoretical
predictions of long spin lifetimes arising from low spin-orbit and hyperfine
couplings. In experiments, however, spin lifetimes in single layer graphene
(SLG) measured via Hanle effects are much shorter than expected theoretically.
Thus, the origin of spin relaxation in SLG is a major issue for graphene
spintronics. Despite extensive theoretical and experimental work addressing
this question, there is still little clarity on the microscopic origin of spin
relaxation. By using organic ligand-bound nanoparticles as charge reservoirs to
tune mobility between 2700 and 12000 cm2/Vs, we successfully isolate the effect
of charged impurity scattering on spin relaxation in SLG. Our results
demonstrate that while charged impurities can greatly affect mobility, the spin
lifetimes are not affected by charged impurity scattering.Comment: 13 pages, 5 figure
Le Chatelier principle in replicator dynamics
The Le Chatelier principle states that physical equilibria are not only
stable, but they also resist external perturbations via short-time
negative-feedback mechanisms: a perturbation induces processes tending to
diminish its results. The principle has deep roots, e.g., in thermodynamics it
is closely related to the second law and the positivity of the entropy
production. Here we study the applicability of the Le Chatelier principle to
evolutionary game theory, i.e., to perturbations of a Nash equilibrium within
the replicator dynamics. We show that the principle can be reformulated as a
majorization relation. This defines a stability notion that generalizes the
concept of evolutionary stability. We determine criteria for a Nash equilibrium
to satisfy the Le Chatelier principle and relate them to mutualistic
interactions (game-theoretical anticoordination) showing in which sense
mutualistic replicators can be more stable than (say) competing ones. There are
globally stable Nash equilibria, where the Le Chatelier principle is violated
even locally: in contrast to the thermodynamic equilibrium a Nash equilibrium
can amplify small perturbations, though both this type of equilibria satisfy
the detailed balance condition.Comment: 12 pages, 3 figure
Parton model versus color dipole formulation of the Drell-Yan process
In the kinematical region where the center of mass energy is much larger than
all other scales, the Drell-Yan process can be formulated in the target rest
frame in terms of the same color dipole cross section as low Bjorken-x deep
inelastic scattering. Since the mechanisms for heavy dilepton production appear
very different in the dipole approach and in the conventional parton model, one
may wonder whether these two formulations really represent the same physics. We
perform a comparison of numerical calculations in the color dipole approach
with calculations in the next-to-leading order parton model. For proton-proton
scattering, the results are very similar at low x_2 from fixed target to RHIC
energies, confirming the close connection between these two very different
approaches. We also compare the transverse momentum distributions of Drell-Yan
dileptons predicted in both formulations. The range of applicability of the
dipole formulation and the impact of future Drell-Yan data from RHIC for
determining the color dipole cross section are discussed. A detailed derivation
of the dipole formulation of the Drell-Yan process is also included.Comment: 20 pages, 5 figure
Patterns of basal signaling heterogeneity can distinguish cellular populations with different drug sensitivities
Non small cell lung cancer H460 clones exhibit a high degree of heterogeneity in signaling states.Clones with similar patterns of basal signaling heterogeneity have similar paclitaxel sensitivities.Models of signaling heterogeneity among the clones can be used to classify sensitivity to paclitaxel for other cancer populations
Long-Term ERK Inhibition in
Induction of compensatory mechanisms and ERK reactivation has limited the effectiveness of Raf and MEK inhibitors in -mutant cancers. We determined that direct pharmacologic inhibition of ERK suppressed the growth of a subset of -mutant pancreatic cancer cell lines and that concurrent phosphatidylinositol 3-kinase (PI3K) inhibition caused synergistic cell death. Additional combinations that enhanced ERK inhibitor action were also identified. Unexpectedly, long-term treatment of sensitive cell lines caused senescence, mediated in part by MYC degradation and p16 reactivation. Enhanced basal PI3K-AKT-mTOR signaling was associated with de novo resistance to ERK inhibitor, as were other protein kinases identified by kinome-wide siRNA screening and a genetic gain-of-function screen. Our findings reveal distinct consequences of inhibiting this kinase cascade at the level of ERK
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