13,813 research outputs found
An eco-solution for track & trace of goods and third party logistics
This paper presents a new economic cost-effective solution known as the Web and telephony based method for tracking and tracing of goods and small and medium sized third party logistic providers. Considering that these companies usually operate on very flat margins, a comparison is made of the available track and trace technologies like GPS, mobile phone approximated GPS and Java based cell tracking in terms of costs, operating risks, and other evaluation criteria
Multireference Correlation in Long Molecules with the Quadratic Scaling Density Matrix Renormalization Group
We have devised and implemented a local ab initio Density Matrix
Renormalization Group (DMRG) algorithm to describe multireference nondynamic
correlations in large systems. For long molecules that are extended in one of
their spatial dimensions, this method allows us to obtain an exact
characterisation of correlation, in the given basis, with a cost that scales
only quadratically with the size of the system. The reduced scaling is achieved
solely through integral screening and without the construction of correlation
domains. We demonstrate the scaling, convergence, and robustness of the
algorithm in polyenes and hydrogen chains. We converge to exact correlation
energies (with 1-10 microhartree precision) in all cases and correlate up to
100 electrons in 100 active orbitals. We further use our algorithm to obtain
exact energies for the metal-insulator transition in hydrogen chains and
compare and contrast our results with those from conventional quantum chemical
methods.Comment: 14 pages, 12 figures, tciLaTeX, aip-BibTeX styl
Entanglement growth in quench dynamics with variable range interactions
Studying entanglement growth in quantum dynamics provides both insight into
the underlying microscopic processes and information about the complexity of
the quantum states, which is related to the efficiency of simulations on
classical computers. Recently, experiments with trapped ions, polar molecules,
and Rydberg excitations have provided new opportunities to observe dynamics
with long-range interactions. We explore nonequilibrium coherent dynamics after
a quantum quench in such systems, identifying qualitatively different behavior
as the exponent of algebraically decaying spin-spin interactions in a
transverse Ising chain is varied. Computing the build-up of bipartite
entanglement as well as mutual information between distant spins, we identify
linear growth of entanglement entropy corresponding to propagation of
quasiparticles for shorter range interactions, with the maximum rate of growth
occurring when the Hamiltonian parameters match those for the quantum phase
transition. Counter-intuitively, the growth of bipartite entanglement for
long-range interactions is only logarithmic for most regimes, i.e.,
substantially slower than for shorter range interactions. Experiments with
trapped ions allow for the realization of this system with a tunable
interaction range, and we show that the different phenomena are robust for
finite system sizes and in the presence of noise. These results can act as a
direct guide for the generation of large-scale entanglement in such
experiments, towards a regime where the entanglement growth can render existing
classical simulations inefficient.Comment: 17 pages, 7 figure
Orbital Optimization in the Density Matrix Renormalization Group, with applications to polyenes and \beta-carotene
In previous work we have shown that the Density Matrix Renormalization Group
(DMRG) enables near-exact calculations in active spaces much larger than are
possible with traditional Complete Active Space algorithms. Here, we implement
orbital optimisation with the Density Matrix Renormalization Group to further
allow the self-consistent improvement of the active orbitals, as is done in the
Complete Active Space Self-Consistent Field (CASSCF) method. We use our
resulting DMRGCASSCF method to study the low-lying excited states of the
all-trans polyenes up to C24H26 as well as \beta-carotene, correlating with
near-exact accuracy the optimised complete \pi-valence space with up to 24
active electrons and orbitals, and analyse our results in the light of the
recent discovery from Resonance Raman experiments of new optically dark states
in the spectrum.Comment: 16 pages, 8 figure
Impact of exercise on articular cartilage in people at risk of, or with established, knee osteoarthritis: a systematic review of randomised controlled trials
This project is supported by a European Union Seventh Framework Programme (FP7-PEOPLE-2013-ITN; KNEEMO) under grant agreement number 607510.Peer reviewedPostprin
Consumption of French-press coffee raises cholesteryl ester transfer protein activity levels before LDL cholesterol in normolipidemic subjects
Compact magneto-optical sources of slow atoms
Three different configurations of compact magneto-optical sources of slow Rb
atoms(LVIS, 2D(+)-MOT and 2D-MOT) were compared with each other at fixed
geometry of cooling laser beams. A precise control of the intensity balances
between the four separate transverse cooling laser beams provided a total
continuous flux of cold atoms from the LVIS and 2D(+)-MOT sources about 8x10^9
atoms/s at total laser power of 60 mW. The flux was measured directly from the
loading rate of a 3D-MOT, placed 34 cm downstream from the sources. Average
velocities of the cooled atomic beam for the LVIS and 2D(+)-MOT sources were
about 8.5 m/s and 11 m/s respectively. An essential advantage of the compact
magneto-optical sources is that their background flux of thermal atoms is two
to three orders of the magnitude smaller than the flux of slow atoms.Comment: 12 pages, 10 figures. to be published in Optics Communication
Theoretical calculations for solid oxygen under high pressure
The crystal structure of solid oxygen at low temperatures and at pressures up
to 7 GPa is studied by theoretical calculations. In the calculations, the
adiabatic potential of the crystal is approximated by a superposition of
pair-potentials between oxygen molecules calculated by an ab-initio method. The
monoclinic alpha structure is stable up to 6 GPa and calculated lattice
parameters agree well with experiments. The origin of a distortion and that of
an anisotropic lattice compressibility of the basal plane of alpha-O2 are
clearly demonstrated. In the pressure range from 6 to 7 GPa, two kinds of
structures are proposed by X-ray diffraction experiments: the alpha and
orthorhombic delta structures. It is found that the energy difference between
these structures becomes very small in this pressure range. The relation
between this trend and the incompatible results of X-ray diffraction
experiments is discussed.Comment: 12 pages, 6 figure
The crucial importance of the -- hybridization in transition metal oxides
We studied the influence of the trigonal distortion of the regular octahedron
along the (111) direction, found in the layers. Under such a
distortion the orbitals split into one and two degenerated
orbitals. We focused on the relative order of these orbitals.
Using quantum chemical calculations of embedded clusters at different levels of
theory, we analyzed the influence of the different effects not taken into
account in the crystalline field theory; that is metal-ligand hybridization,
long-range crystalline field, screening effects and orbital relaxation. We
found that none of them are responsible for the relative order of the
orbitals. In fact, the trigonal distortion allows a mixing of the and
orbitals of the metallic atom. This hybridization is at the origin of the
-- relative order and of the incorrect prediction of the
crystalline field theory
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