13,158 research outputs found
Unforeseen high temperature and humidity stability of FeCl intercalated few layer graphene
We present the first systematic study of the stability of the structure and
electrical properties of FeCl intercalated few-layer graphene to high
levels of humidity and high temperature. Complementary experimental techniques
such as electrical transport, high resolution transmission electron microscopy
and Raman spectroscopy conclusively demonstrate the unforeseen stability of
this transparent conductor to a relative humidity up to at room
temperature for 25 days, to a temperature up to 150\,^\circC in atmosphere
and up to a temperature as high as 620\,^\circC in vacuum, that is more than
twice higher than the temperature at which the intercalation is conducted. The
stability of FeCl intercalated few-layer graphene together with its unique
values of low square resistance and high optical transparency, makes this
material an attractive transparent conductor in future flexible electronic
applications.Comment: Scientific Reports, volume 5, article no. 760
Observation of blue-shifted ultralong-range Cs Rydberg molecules
We observe ultralong-range blue-shifted Cs molecular states near
Rydberg states in an optical dipole trap, where .
The accidental near degeneracy of and Rydberg states for in
Cs, due to the small fractional quantum defect, leads to non-adiabatic
coupling among these states, producing potential wells above the
thresholds. Two important consequences of admixing high angular momentum states
with states are the formation of large permanent dipole moments, Debye, and accessibility of these states via two-photon association.
The observed states are in excellent agreement with theory. Both projections of
the total angular momentum on the internuclear axis are visible in the
experiment
Monte Carlo Determination of Multiple Extremal Eigenpairs
We present a Monte Carlo algorithm that allows the simultaneous determination
of a few extremal eigenpairs of a very large matrix without the need to compute
the inner product of two vectors or store all the components of any one vector.
The new algorithm, a Monte Carlo implementation of a deterministic one we
recently benchmarked, is an extension of the power method. In the
implementation presented, we used a basic Monte Carlo splitting and termination
method called the comb, incorporated the weight cancellation method of Arnow
{\it et al.}, and exploited a new sampling method, the sewing method, that does
a large state space sampling as a succession of small state space samplings. We
illustrate the effectiveness of the algorithm by its determination of the two
largest eigenvalues of the transfer matrices for variously-sized
two-dimensional, zero field Ising models. While very likely useful for other
transfer matrix problems, the algorithm is however quite general and should
find application to a larger variety of problems requiring a few dominant
eigenvalues of a matrix.Comment: 22 pages, no figure
Convergence of many-body wavefunction expansions using a plane wave basis: from the homogeneous electron gas to the solid state
Using the finite simulation-cell homogeneous electron gas (HEG) as a model,
we investigate the convergence of the correlation energy to the complete basis
set (CBS) limit in methods utilising plane-wave wavefunction expansions. Simple
analytic and numerical results from second-order M{\o}ller-Plesset theory (MP2)
suggest a 1/M decay of the basis-set incompleteness error where M is the number
of plane waves used in the calculation, allowing for straightforward
extrapolation to the CBS limit. As we shall show, the choice of basis set
truncation when constructing many-electron wavefunctions is far from obvious,
and here we propose several alternatives based on the momentum transfer vector,
which greatly improve the rate of convergence. This is demonstrated for a
variety of wavefunction methods, from MP2 to coupled-cluster doubles theory
(CCD) and the random-phase approximation plus second-order screened exchange
(RPA+SOSEX). Finite basis-set energies are presented for these methods and
compared with exact benchmarks. A transformation can map the orbitals of a
general solid state system onto the HEG plane wave basis and thereby allow
application of these methods to more realistic physical problems.Comment: 15 pages, 9 figure
The flux distribution of the three quark system in SU(3)
We study the abelian color-flux distribution of the three quark system in the
maximally abelian gauge on SU(3) lattices. The distribution of the color
electric field suggests , which might be interpreted through the dual
superconductor picture as the result of the vacuum pressure in the confined
phase. In order to clarify the flux structure, we investigate the color
electric field in the three quark system also in the monopole part and in the
photon part.Comment: 3pages, 5figures, Lattice2002(topology
Fundamental properties and applications of quasi-local black hole horizons
The traditional description of black holes in terms of event horizons is
inadequate for many physical applications, especially when studying black holes
in non-stationary spacetimes. In these cases, it is often more useful to use
the quasi-local notions of trapped and marginally trapped surfaces, which lead
naturally to the framework of trapping, isolated, and dynamical horizons. This
framework allows us to analyze diverse facets of black holes in a unified
manner and to significantly generalize several results in black hole physics.
It also leads to a number of applications in mathematical general relativity,
numerical relativity, astrophysics, and quantum gravity. In this review, I will
discuss the basic ideas and recent developments in this framework, and
summarize some of its applications with an emphasis on numerical relativity.Comment: 14 pages, 2 figures. Based on a talk presented at the 18th
International Conference on General Relativity and Gravitation, 8-13 July
2007, Sydney, Australi
Flux Tubes of Two- and Three-Quark System in Full QCD
We study the abelian color flux of two- and three-quark systems in the
maximally abelian gauge in lattice QCD with dynamical fermions. We find that
the abelian flux tube formed between quark and antiquark is very much the same
as in quenched QCD up to quark separations of 2fm. The profile of the
color electric field in three-quark system suggests ansatz, which might be
interpreted as the result of the vacuum pressure in the confined phase. In
order to clarify the flux structure, we investigate the color electric field of
the three-quark system splittting the abelian gauge field into the monopole and
photon parts.Comment: 4 pages, 4 figures, Talk given at XVI International Conference on
Particles and Nuclei (PaNic02),Osaka, Japan, Sep.30 - Oct.4, 200
Serum lactate on admission to intensive care and outcome: an observational cohort study
No abstract available
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