2,554 research outputs found
Leaf stripe resistance of spring barley cultivars
Results of six years of screening trials clearly indicate that effective resistance against barley leaf stripe is available, also in modern cultivars. Among the spring barley cultivars that are currently most widely grown in Denmark, Cabaret, Troon, Sebastian, Justina and Brazil appear most resistant, but only Brazil combines a favourable resistance performance (= low mean and standard deviation of environment-adjusted leaf stripe incidence) with a high number of observations (= years of testing). However, the cultivars appearing most resistant over the years are relatively old ones such as Vada, Alabama, Odin and particularly Scarlett, which has been resistant in all years in which it was tested. Amongst the new cultivars, Marigold, Native and SW Immer appear to have the most promising resistance properties so far. However, they have only been tested in two years of which only one had reasonably high infection levels. The results furthermore indicate huge year-to-year variation in infection levels, presumably due to variation in environmental conditions related to leaf stripe infection
High damage potential of seed-borne spot blotch in organically grown spring barley in Denmark
Spot blotch of barley (Bipolaris sorokiniana, perfect state: Cochliobolus sativus) occurs wherever barley is grown but is normally not considered a major problem in Danish barley production. It is therefore not included in routine disease surveys or official variety testing in Denmark. However, recommended seed contamination thresholds are 30% for spring barley and 15% for winter barley. Several spring barley varieties were grown under organic (no seed dressing, mechanical weeding) and conventional (seed dressing with fungicides, herbicide application) production conditions at three sites in Denmark in 2003. The harvested seeds were analysed for contamination levels of seed-borne B. sorokiniana using a blotter method. The percentage of seeds contaminated with B. sorokiniana ranged from about 5 to 95 % and was highly depending on the site, production system and variety. Contamination levels of organically cultivated plots were about twice as high as those of plots receiving conventional treatments. The germinating ability of seeds was highly affected by the level of B. sorokiniana contamination and declined drastically at contamination levels above 60%. This effect appeared to differ among varieties. The 1000-grain weight was not affected by the level of spot blotch contamination of seeds. The results indicate that the importance of spot blotch may be underrated, especially in organic barley production and that the role of varietal resistance should be investigated. More results are expected from ongoing seed analyses
Location-Quality-aware Policy Optimisation for Relay Selection in Mobile Networks
Relaying can improve the coverage and performance of wireless access
networks. In presence of a localisation system at the mobile nodes, the use of
such location estimates for relay node selection can be advantageous as such
information can be collected by access points in linear effort with respect to
number of mobile nodes (while the number of links grows quadratically).
However, the localisation error and the chosen update rate of location
information in conjunction with the mobility model affect the performance of
such location-based relay schemes; these parameters also need to be taken into
account in the design of optimal policies. This paper develops a Markov model
that can capture the joint impact of localisation errors and inaccuracies of
location information due to forwarding delays and mobility; the Markov model is
used to develop algorithms to determine optimal location-based relay policies
that take the aforementioned factors into account. The model is subsequently
used to analyse the impact of deployment parameter choices on the performance
of location-based relaying in WLAN scenarios with free-space propagation
conditions and in an measurement-based indoor office scenario.Comment: Accepted for publication in ACM/Springer Wireless Network
Fast simulation of stabilizer circuits using a graph state representation
According to the Gottesman-Knill theorem, a class of quantum circuits, namely
the so-called stabilizer circuits, can be simulated efficiently on a classical
computer. We introduce a new algorithm for this task, which is based on the
graph-state formalism. It shows significant improvement in comparison to an
existing algorithm, given by Gottesman and Aaronson, in terms of speed and of
the number of qubits the simulator can handle. We also present an
implementation.Comment: v2: significantly improved presentation; accepted by PR
Resistente bygsorter begrænser problemer med bladplet i økologisk såsæd
Seed born net blotch is a threat to the organic barley seed production in Denmark because it often exceeds the legal 15% infestation threshold in organically produced barley seed lots. Relationships among initial seed infestation levels, disease development during the growing season, yield parameters and net blotch infestation of the harvested grains were examined. Highly significant positive correlations among initial seed infestation, primary infection of seedlings and disease severity during the growing season as well as among disease severity at flowering and infestation of the harvested grains were found. The seed infestation level was much less than proportionally related to the primary infection of seedlings and to the disease severity later in the season. All these variables were negatively correlated with single grain weight, fraction of large grains and total yield. Varietal resistance appeared to be a key determinant for disease severity and seed infestation. The results will be used to help develop more flexible net blotch infestation thresholds for organically produced barley seeds
Fidelity decay for local perturbations: microwave evidence for oscillating decay exponents
We study fidelity decay in classically chaotic microwave billiards for a local, piston-like boundary perturbation. We experimentally verify a predicted non-monotonic cross-over from the Fermi Golden Rule to the escape-rate regime of the Loschmidt echo decay with increasing local boundary perturbation. In particular, we observe pronounced oscillations of the decay rate as a function of the piston position which quantitatively agree with corresponding theoretical results based on a refined semiclassical approach for local boundary perturbations
Quantum communication cost of preparing multipartite entanglement
We study the preparation and distribution of high-fidelity multi-party
entangled states via noisy channels and operations. In the particular case of
GHZ and cluster states, we study different strategies using bipartite or
multipartite purification protocols. The most efficient strategy depends on the
target fidelity one wishes to achieve and on the quality of transmission
channel and local operations. We show the existence of a crossing point beyond
which the strategy making use of the purification of the state as a whole is
more efficient than a strategy in which pairs are purified before they are
connected to the final state. We also study the efficiency of intermediate
strategies, including sequences of purification and connection. We show that a
multipartite strategy is to be used if one wishes to achieve high fidelity,
whereas a bipartite strategy gives a better yield for low target fidelity.Comment: 21 pages, 17 figures; accepted for publication in Phys. Rev. A; v2:
corrections in figure
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