1,891 research outputs found
QCD finite T transition -- Comparison between Wilson and staggered results
A quantitative comparison between the finite temperature behaviour of the
staggered and Wilson fermion formulations are performed. The comparison is
based on a physical quantity that is expected to be quite sensitive to the
fermionic features of the action. For that purpose we use the height of the
peak for , where is the quark number susceptibility.Comment: 6 pages. Talk presented at Lattice 200
Enhancement of surface activity in CO oxidation on Pt(110) through spatiotemporal laser actuation
We explore the effect of spatiotemporally varying substrate temperature
profiles on the dynamics and resulting reaction rate enhancement for the
catalytic oxidation of CO on Pt(110). The catalytic surface is "addressed" by a
focused laser beam whose motion is computer-controlled. The averaged reaction
rate is observed to undergo a characteristic maximum as a function of the speed
of this moving laser spot. Experiments as well as modelling are used to explore
and rationalize the existence of such an optimal laser speed.Comment: 9 pages, 12 figures, submitted to Phys. Rev.
Traits in Lepidoptera assemblages are differently influenced by local and landscape scale factors in farmland habitat islands
Semi-natural grassland islands have a key role in slowing down biodiversity decline in intensively cultivated agricultural landscapes. Assemblages in such habitat patches are not only limited by local habitat quality, but are also influenced by the suitability and distribution of different habitat types in the surrounding landscape. If we want to preserve a functionally diverse Lepidoptera fauna, both local and landscape scale environmental effects, including land use and management, should be considered. In the present study, we describe trait-based characteristics of noctuid dominated macro-moth assemblages (MMAs) in grassland remnants of an intensively cultivated agricultural area. By gathering environmental data from local to landscape scales, we aimed to identify the most influential scales, possible interactions between scales and the role of integrated arable fields in shaping MMAs. We conducted abundance weighted trait-based multivariate analysis of the assemblages based on six trait groups. Both local and landscape scale variables had important influence, acting on different traits of the assemblages. By variance partitioning, we could identify variables that exerted maximal effect at 50 m and 250 m radii circles. Variables describing local vegetation and identity of neighbouring crop were responsible for species richness and rarity status, while the area of arable and wooded habitats within 250 m were responsible for total catch and pest status related traits. There was significant interaction between principal components axes representing local and landscape variables. Rarity, more than other traits, was influenced by the interaction. Integrated fields had no effect on MMAs. The present study highlights the contributions of both local and landscape scales to the shaping of MMAs and suggests that the preservation of both local habitat quality and landscape heterogeneity are important if we would like to maintain species rich and functionally diverse Lepidoptera fauna
Enhanced thermal stability and spin-lattice relaxation rate of N@C60 inside carbon nanotubes
We studied the temperature stability of the endohedral fullerene molecule,
N@C60, inside single-wall carbon nanotubes using electron spin resonance
spectroscopy. We found that the nitrogen escapes at higher temperatures in the
encapsulated material as compared to its pristine, crystalline form. The
temperature dependent spin-lattice relaxation time, T_1, of the encapsulated
molecule is significantly shorter than that of the crystalline material, which
is explained by the interaction of the nitrogen spin with the conduction
electrons of the nanotubes.Comment: 5 pages, 4 figures, 1 tabl
Rigorous results on spontaneous symmetry breaking in a one-dimensional driven particle system
We study spontaneous symmetry breaking in a one-dimensional driven
two-species stochastic cellular automaton with parallel sublattice update and
open boundaries. The dynamics are symmetric with respect to interchange of
particles. Starting from an empty initial lattice, the system enters a symmetry
broken state after some time T_1 through an amplification loop of initial
fluctuations. It remains in the symmetry broken state for a time T_2 through a
traffic jam effect. Applying a simple martingale argument, we obtain rigorous
asymptotic estimates for the expected times ~ L ln(L) and ln() ~ L,
where L is the system size. The actual value of T_1 depends strongly on the
initial fluctuation in the amplification loop. Numerical simulations suggest
that T_2 is exponentially distributed with a mean that grows exponentially in
system size. For the phase transition line we argue and confirm by simulations
that the flipping time between sign changes of the difference of particle
numbers approaches an algebraic distribution as the system size tends to
infinity.Comment: 23 pages, 7 figure
Detection of multipartite entanglement with two-body correlations
We show how to detect entanglement with criteria built from simple two-body
correlation terms. Since many natural Hamiltonians are sums of such correlation
terms, our ideas can be used to detect entanglement by energy measurement. Our
criteria can straightforwardly be applied for detecting different forms of
multipartite entanglement in familiar spin models in thermal equilibrium.Comment: 5 pages including 2 figures, LaTeX; for the proceedings of the DPG
spring meeting, Berlin, March 200
Spectral functions of charmonium with 2+1 flavours of dynamical quarks
Finite temperature charmonium spectral functions in the pseudoscalar(PS) and
vector(V) channels are studied in lattice QCD with 2+1 flavours of dynamical
Wilson quarks, on fine isotropic lattices (with a lattice spacing of 0.057fm),
with a non-physical pion mass of 545MeV. The highest temperature studied is
approximately 1.4Tc. Up to this temperature no significant variation of the
spectral function is seen in the PS channel. The V channel shows some
temperature dependence, which seems to be consistent with a temperature
dependent low frequency peak related to heavy quark transport, plus a
temperature independent term at omega > 0. These results are in accord with
previous calculations using the quenched approximation.Comment: Conference proceedings: The 32nd International Symposium on Lattice
Field Theory - Lattice 2014 June 23-28, 2014 Columbia University, New York,
New York This conference contribution draws heavily from the paper:
arXiv:1401.5940 [hep-lat
Hydrodynamics of topological defects in nematic liquid crystals
We show that back-flow, the coupling between the order parameter and the
velocity fields, has a significant effect on the motion of defects in nematic
liquid crystals. In particular the defect speed can depend strongly on the
topological strength in two dimensions and on the sense of rotation of the
director about the core in three dimensions.Comment: 4 pages including two figure
Achieving Good Angular Resolution in 3D Arc Diagrams
We study a three-dimensional analogue to the well-known graph visualization
approach known as arc diagrams. We provide several algorithms that achieve good
angular resolution for 3D arc diagrams, even for cases when the arcs must
project to a given 2D straight-line drawing of the input graph. Our methods
make use of various graph coloring algorithms, including an algorithm for a new
coloring problem, which we call localized edge coloring.Comment: 12 pages, 5 figures; to appear at the 21st International Symposium on
Graph Drawing (GD 2013
Political and cultural impacts of growing inequalities
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