399 research outputs found
Entanglement quantification through local observable correlations
We present a significantly improved scheme of entanglement detection inspired
by local uncertainty relations for a system consisting of two qubits.
Developing the underlying idea of local uncertainty relations, namely
correlations, we demonstrate that it's possible to define a measure which is
invariant under local unitary transformations and which is based only on local
measurements. It is quite simple to implement experimentally and it allows
entanglement quantification in a certain range for mixed states and exactly for
pure states, without first obtaining full knowledge (e.g. through tomography)
of the state.Comment: 5 pages, 3 figures, revised version with new proof and replaced
figure
Involvement of siderophores in the reduction of metal-induced inhibition of auxin synthesis in Streptomyces spp.
Ectomycorrhizal influence on the dynamics of sesquiterpene release by Tricholoma vaccinum
Tricholoma vaccinum is an ectomycorrhizal basidiomycete with high host specificity. The slow-growing fungus is able to produce twenty sesquiterpenes, including α-barbatene, sativene, isocaryophyllene, α-cuprenene, β-cedrene, ß-copaene, 4-epi-α-acoradiene, and chamigrene in axenic culture. For the three major compounds, Δ(6)-protoilludene, β-barbatene, and an unidentified oxygenated sesquiterpene (m/z 218.18), changed production during co-cultivation with the ectomycorrhizal partner tree, Picea abies, could be shown with distinct dynamics. During the mycorrhizal growth of T. vaccinum–P. abies, Δ(6)-protoilludene and the oxygenated sesquiterpene appeared at similar times, which warranted further studies of potential biosynthesis genes. In silico analyses identified a putative protoilludene synthesis gene, pie1, as being up-regulated in the mycorrhizal stage, in addition to the previously identified, co-regulated geosmin synthase, ges1. We therefore hypothesize that the sesquiterpene synthase pie1 has an important role during mycorrhization, through Δ(6)-protoilludene and/or its accompanied oxygenated sesquiterpene production
Experimental entanglement verification and quantification via uncertainty relations
We report on experimental studies on entanglement quantification and
verification based on uncertainty relations for systems consisting of two
qubits. The new proposed measure is shown to be invariant under local unitary
transformations, by which entanglement quantification is implemented for
two-qubit pure states. The nonlocal uncertainty relations for two-qubit pure
states are also used for entanglement verification which serves as a basic
proposition and promise to be a good choice for verification of multipartite
entanglement.Comment: 5 pages, 3 figures and 2 table
Crossing barriers in planetesimal formation: The growth of mm-dust aggregates with large constituent grains
Collisions of mm-size dust aggregates play a crucial role in the early phases
of planet formation. We developed a laboratory setup to observe collisions of
dust aggregates levitating at mbar pressures and elevated temperatures of 800
K. We report on collisions between basalt dust aggregates of from 0.3 to 5 mm
in size at velocities between 0.1 and 15 cm/s. Individual grains are smaller
than 25 \mum in size. We find that for all impact energies in the studied range
sticking occurs at a probability of 32.1 \pm 2.5% on average. In general, the
sticking probability decreases with increasing impact parameter. The sticking
probability increases with energy density (impact energy per contact area). We
also observe collisions of aggregates that were formed by a previous sticking
of two larger aggregates. Partners of these aggregates can be detached by a
second collision with a probability of on average 19.8 \pm 4.0%. The measured
accretion efficiencies are remarkably high compared to other experimental
results. We attribute this to the rel. large dust grains used in our
experiments, which make aggregates more susceptible to restructuring and energy
dissipation. Collisional hardening by compaction might not occur as the
aggregates are already very compact with only 54 \pm 1% porosity. The
disassembly of previously grown aggregates in collisions might stall further
aggregate growth. However, owing to the levitation technique and the limited
data statistics, no conclusive statement about this aspect can yet be given. We
find that the detachment efficiency decreases with increasing velocities and
accretion dominates in the higher velocity range. For high accretion
efficiencies, our experiments suggest that continued growth in the mm-range
with larger constituent grains would be a viable way to produce larger
aggregates, which might in turn form the seeds to proceed to growing
planetesimals.Comment: 9 pages, 20 figure
Amplitude measurements of Faraday waves
A light reflection technique is used to measure quantitatively the surface
elevation of Faraday waves. The performed measurements cover a wide parameter
range of driving frequencies and sample viscosities. In the capillary wave
regime the bifurcation diagrams exhibit a frequency independent scaling
proportional to the wavelength. We also provide numerical simulations of the
full Navier-Stokes equations, which are in quantitative agreement up to
supercritical drive amplitudes of 20%. The validity of an existing perturbation
analysis is found to be limited to 2.5% overcriticaly.Comment: 7 figure
Capillary filling with wall corrugations] Capillary filling in microchannels with wall corrugations: A comparative study of the Concus-Finn criterion by continuum, kinetic and atomistic approaches
We study the impact of wall corrugations in microchannels on the process of
capillary filling by means of three broadly used methods - Computational Fluid
Dynamics (CFD), Lattice-Boltzmann Equations (LBE) and Molecular Dynamics (MD).
The numerical results of these approaches are compared and tested against the
Concus-Finn (CF) criterion, which predicts pinning of the contact line at
rectangular ridges perpendicular to flow for contact angles theta > 45. While
for theta = 30, theta = 40 (no flow) and theta = 60 (flow) all methods are
found to produce data consistent with the CF criterion, at theta = 50 the
numerical experiments provide different results. Whilst pinning of the liquid
front is observed both in the LB and CFD simulations, MD simulations show that
molecular fluctuations allow front propagation even above the critical value
predicted by the deterministic CF criterion, thereby introducing a sensitivity
to the obstacle heigth.Comment: 25 pages, 8 figures, Langmuir in pres
Measurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2
We report on a measurement of the parity-violating asymmetry in the
scattering of longitudinally polarized electrons on unpolarized protons at a
of 0.230 (GeV/c)^2 and a scattering angle of \theta_e = 30^o - 40^o.
Using a large acceptance fast PbF_2 calorimeter with a solid angle of
\Delta\Omega = 0.62 sr the A4 experiment is the first parity violation
experiment to count individual scattering events. The measured asymmetry is
A_{phys} =(-5.44 +- 0.54_{stat} +- 0.27_{\rm sys}) 10^{-6}. The Standard Model
expectation assuming no strangeness contributions to the vector form factors is
. The difference is a direct measurement of the
strangeness contribution to the vector form factors of the proton. The
extracted value is G^s_E + 0.225 G^s_M = 0.039 +- 0.034 or F^s_1 + 0.130 F^s_2
= 0.032 +- 0.028.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Letters on Dec 11, 200
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