4,188 research outputs found
Changes in yield and composition of barley, wheat and triticale grains harvested during advancing stages of ripening
peer-reviewedThis study involved an evaluation of the changes in grain yield, nutritive value, ensilability
and harvesting losses of intensively managed winter cereals harvested during
the advancing stages of ripening. Five cereal crops (barley cv. Regina and wheat cv.
Madrigal in 2001; barley cv. Regina, wheat cv. Falstaff and triticale cv. Fidelio in 2002)
were assessed. Twenty plots per crop were arranged in a randomised complete block
design, with five times of harvest (four for barley in 2002) and four replicate blocks
per harvest. Dry matter (DM) yields changed relatively little between harvest dates,
but fresh yields declined (P < 0.001) over time due to the moisture loss associated with
ripening. Time-course changes in indices of nutritive value, such as concentrations of
crude protein, starch and ash, and organic matter digestibility, were relatively small
and did not follow a consistent pattern. Ensilability indices, such as DM and watersoluble
carbohydrate concentrations and buffering capacity, indicated that satisfactory
fermentations were likely if such crops were ensiled; buffering capacity, generally
declining with advancing maturity. Harvesting losses were not clearly related to growth
stage at harvest. It is concluded that winter cereal grain (barley, wheat and triticale)
DM yields and quality were relatively constant as ripening progressed from DM concentrations
of around 550 to >800 g/kg.One of the authors (P.S.) was in receipt
of a Teagasc Walsh Fellowship
A microfabricated ion trap with integrated microwave circuitry
We describe the design, fabrication and testing of a surface-electrode ion
trap, which incorporates microwave waveguides, resonators and coupling elements
for the manipulation of trapped ion qubits using near-field microwaves. The
trap is optimised to give a large microwave field gradient to allow
state-dependent manipulation of the ions' motional degrees of freedom, the key
to multiqubit entanglement. The microwave field near the centre of the trap is
characterised by driving hyperfine transitions in a single laser-cooled 43Ca+
ion.Comment: 4 pages, 5 figure
Diffusion in a Time-dependent External Field
The problem of diffusion in a time-dependent (and generally inhomogeneous)
external field is considered on the basis of a generalized master equation with
two times, introduced in [1,2]. We consider the case of the quasi Fokker-Planck
approximation, when the probability transition function for diffusion
(PTD-function) does not possess a long tail in coordinate space and can be
expanded as a function of instantaneous displacements. The more complicated
case of long tails in the PTD will be discussed separately. We also discuss
diffusion on the basis of hydrodynamic and kinetic equations and show the
validity of the phenomenological approach. A new type of "collision" integral
is introduced for the description of diffusion in a system of particles, which
can transfer from a moving state to the rest state (with some waiting time
distribution). The solution of the appropriate kinetic equation in the external
field also confirms the phenomenological approach of the generalized master
equation.Comment: 18 pages, no figure
Extensions of C*-dynamical systems to systems with complete transfer operators
Starting from an arbitrary endomorphism of a unital C*-algebra
we construct a bigger C*-algebra and extend onto in such a way
that the extended endomorphism has a unital kernel and a hereditary
range, i.e. there exists a unique non-degenerate transfer operator for
, called the complete transfer operator. The pair is
universal with respect to a suitable notion of a covariant representation and
depends on a choice of an ideal in . The construction enables a natural
definition of the crossed product for arbitrary .Comment: Compressed and submitted version, 9 page
Deterministic entanglement and tomography of ion spin qubits
We have implemented a universal quantum logic gate between qubits stored in
the spin state of a pair of trapped calcium 40 ions. An initial product state
was driven to a maximally entangled state deterministically, with 83% fidelity.
We present a general approach to quantum state tomography which achieves good
robustness to experimental noise and drift, and use it to measure the spin
state of the ions. We find the entanglement of formation is 0.54.Comment: 3 figures, 4 pages, footnotes fixe
Long-lived mesoscopic entanglement outside the Lamb-Dicke regime
We create entangled states of the spin and motion of a single Ca
ion in a linear ion trap. The motional part consists of coherent states of
large separation and long coherence time. The states are created by driving the
motion using counterpropagating laser beams. We theoretically study and
experimentally observe the behaviour outside the Lamb-Dicke regime, where the
trajectory in phase space is modified and the coherent states become squeezed.
We directly observe the modification of the return time of the trajectory, and
infer the squeezing. The mesoscopic entanglement is observed up to with coherence time 170 microseconds and mean phonon excitation
\nbar = 16.Comment: 5 pages, 3 figures. Revised version after editor comment
Shift of percolation thresholds for epidemic spread between static and dynamic small-world networks
The aim of the study was to compare the epidemic spread on static and dynamic
small-world networks. The network was constructed as a 2-dimensional
Watts-Strogatz model (500x500 square lattice with additional shortcuts), and
the dynamics involved rewiring shortcuts in every time step of the epidemic
spread. The model of the epidemic is SIR with latency time of 3 time steps. The
behaviour of the epidemic was checked over the range of shortcut probability
per underlying bond 0-0.5. The quantity of interest was percolation threshold
for the epidemic spread, for which numerical results were checked against an
approximate analytical model. We find a significant lowering of percolation
thresholds for the dynamic network in the parameter range given. The result
shows that the behaviour of the epidemic on dynamic network is that of a static
small world with the number of shortcuts increased by 20.7 +/- 1.4%, while the
overall qualitative behaviour stays the same. We derive corrections to the
analytical model which account for the effect. For both dynamic and static
small-world we observe suppression of the average epidemic size dependence on
network size in comparison with finite-size scaling known for regular lattice.
We also study the effect of dynamics for several rewiring rates relative to
latency time of the disease.Comment: 13 pages, 6 figure
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