870 research outputs found
Comparison of NIRS based methods to determine legume content of mixed swards
Four established and two new NIRS calibrations for the determination of legume content in dry ground mixtures were used to estimate clover content in ten Finnish red clover-grass mixtures of known legume content
Noise sustained propagation: Local versus global noise
We expand on prior results on noise supported signal propagation in arrays of
coupled bistable elements. We present and compare experimental and numerical
results for kink propagation under the influence of local and global
fluctuations. As demonstrated previously for local noise, an optimum range of
global noise power exists for which the medium acts as a reliable transmission
``channel''. We discuss implications for propagation failure in a model of
cardiac tissue and present a general theoretical framework based on discrete
kink statistics. Valid for generic bistable chains, the theory captures the
essential features ob served in our experiments and numerical simulations.Comment: 1 latex file 20 pages, 9 figures. Accepted for publication in
Physical Review
Data sources for rescuing the rich heritage of Mediterranean historical surface climate data
10.1002/gdj3.4Availability of long-term and high-quality instrumental climate records is still insufficient and the rich heritage of meteorological surface observations is largely underexploited in many parts of the world. This is particularly striking over the Greater Mediterranean region (GMR), where meteorological observations have been taken since the 18th century at some locations. The lack of high quality and long series here is despite this region being regarded as a climate change hot spot. This article mainly assesses relevant sources containing Mediterranean historical climate data and metadata either from online repositories worldwide or physical archives, with the emphasis here on the rich holdings kept at French archives. A particular case study is the data rescue (DARE) program undertaken by the Algerian National Meteorological Service, as well as some of the past and ongoing projects and initiatives aimed at enhancing climate data availability and accessibility over the GMR. Our findings point to the high potential for undertaking DARE activities over the GMR and the need for bringing longer and higher quality climate time series to support a diverse number of scientific and technical assessments and policies
On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at rest
We discuss pion multiplicities and single pion momentum spectra from proton
antiproton annihilation at rest. Both the scaled phase space model and the
Skyrme-coherent state approach describe these observables well. In the coherent
state approach the puzzling size of the scale parameter relating the phase
space integrals for different multiplicities is replaced by a well defined
weight function. The strength of this function is determined by the intensity
of the classical pion field and its spatial extent is of order 1 fm.Comment: 11 pages including 4 figures(postscript
Measurement-free fault-tolerant quantum error correction in near-term devices
Logical qubits can be protected from decoherence by performing QEC cycles
repeatedly. Algorithms for fault-tolerant QEC must be compiled to the specific
hardware platform under consideration in order to practically realize a quantum
memory that operates for in principle arbitrary long times. All circuit
components must be assumed as noisy unless specific assumptions about the form
of the noise are made. Modern QEC schemes are challenging to implement
experimentally in physical architectures where in-sequence measurements and
feed-forward of classical information cannot be reliably executed fast enough
or even at all. Here we provide a novel scheme to perform QEC cycles without
the need of measuring qubits that is fully fault-tolerant with respect to all
components used in the circuit. Our scheme can be used for any low-distance CSS
code since its only requirement towards the underlying code is a transversal
CNOT gate. Similarly to Steane-type EC, we coherently copy errors to a logical
auxiliary qubit but then apply a coherent feedback operation from the auxiliary
system to the logical data qubit. The logical auxiliary qubit is prepared
fault-tolerantly without measurements, too. We benchmark logical failure rates
of the scheme in comparison to a flag-qubit based EC cycle. We map out a
parameter region where our scheme is feasible and estimate physical error rates
necessary to achieve the break-even point of beneficial QEC with our scheme. We
outline how our scheme could be implemented in ion traps and with neutral atoms
in a tweezer array. For recently demonstrated capabilities of atom shuttling
and native multi-atom Rydberg gates, we achieve moderate circuit depths and
beneficial performance of our scheme while not breaking fault tolerance. These
results thereby enable practical fault-tolerant QEC in hardware architectures
that do not support mid-circuit measurements.Comment: 24 pages, 19 figure
Multivariate Anisotropic Interpolation on the Torus
We investigate the error of periodic interpolation, when sampling a function
on an arbitrary pattern on the torus. We generalize the periodic Strang-Fix
conditions to an anisotropic setting and provide an upper bound for the error
of interpolation. These conditions and the investigation of the error
especially take different levels of smoothness along certain directions into
account
Coherent Pion Radiation From Nucleon Antinucleon Annihilation
A unified picture of nucleon antinucleon annihilation into pions emerges from
a classical description of the pion wave produced in annihilation and the
subsequent quantization of that wave as a coherent state. When the constraints
of energy-momentum and iso-spin conservation are imposed on the coherent state,
the pion number distribution and charge ratios are found to be in excellent
agreement with experiment.Comment: LaTex, 8 text pages, 1 PostScript figure, PSI-PR-93-2
Weak pinning and long-range anticorrelated motion of phase boundaries in driven diffusive systems
We show that domain walls separating coexisting extremal current phases in
driven diffusive systems exhibit complex stochastic dynamics, with a
subdiffusive temporal growth of position fluctuations due to long-range
anticorrelated current fluctuations and a weak pinning at long times. This weak
pinning manifests itself in a saturated width of the domain wall position
fluctuations that increases sublinearly with the system size. As a function of
time and system size , the width exhibits a scaling behavior
, with constant for and for . An Orstein-Uhlenbeck process with long-range
anticorrelated noise is shown to capture this scaling behavior. Results for the
drift coefficient of the domain wall motion point to memory effects in its
dynamics.Comment: 6 pages, 4 figures plus 6 pages supplemental material with 3 figure
Systematic Theoretical Search for Dibaryons in a Relativistic Model
A relativistic quark potential model is used to do a systematic search for
quasi-stable dibaryon states in the , , and three flavor world.
Flavor symmetry breaking and channel coupling effects are included and an
adiabatic method and fractional parentage expansion technique are used in the
calculations. The relativistic model predicts dibaryon candidates completely
consistent with the nonrelativistic model.Comment: 12 pages, latex, no figure
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