2,762 research outputs found
Potential food production from forage legume-based-systems in Europe: an overview
peer-reviewedIntensification of EU livestock farming systems has been accompanied by the development of maize silage and intensively fertilised grasses at the expense of forage
legume crops. However in the new context of agriculture, the development of forage
legumes constitutes one of the pillars for future livestock farming systems with high
environmental and economical performances. Yield benefits of grass-clover mixtures
are equivalent fertiliser N inputs of 150 to 350 kg/ha, and productive grass-clover
mixtures can fix 100 to 380 kg N per hectare symbiotically from the atmosphere.
Animal intake of legumes is high and the rate of decline of legume nutritional
quality with advancing maturity is less than for grasses, especially in the case of
white clover, which makes mixed pastures easier to manage. Animal performances
at grazing are identical or higher on clover-enriched pastures. Due to their high
protein concentration, conserved forage legumes fit well with maize silage. Forage
legumes increase the concentration of beneficial α-linolenic acid in ruminant products.
Environmental balance of forage legumes is positive. Increasing the proportion
of white clover at the expense of mineral N fertilisation can reduce the risk of
nitrate leaching. Because forage legumes only require solar energy to fix N from the
air, they also reduce energy consumption and associated impacts. They contribute
to reduce the global warming potential of livestock systems by reducing emission
of enteric methane and nitrous oxide from pasture and crop production. As an
element of arable crop rotations, grass-clover leys suppress pests, diseases and
weeds, improve soil structure and prevent soil erosion and nitrate leaching.
Nevertheless, forage legumes have some limitations: expensive to harvest, difficulties of conservation, management of the associations. To take full advantage of forage legumes in the future, new research and development are required as well as financial support from the EU
On the Connectivity of Unions of Random Graphs
Graph-theoretic tools and techniques have seen wide use in the multi-agent
systems literature, and the unpredictable nature of some multi-agent
communications has been successfully modeled using random communication graphs.
Across both network control and network optimization, a common assumption is
that the union of agents' communication graphs is connected across any finite
interval of some prescribed length, and some convergence results explicitly
depend upon this length. Despite the prevalence of this assumption and the
prevalence of random graphs in studying multi-agent systems, to the best of our
knowledge, there has not been a study dedicated to determining how many random
graphs must be in a union before it is connected. To address this point, this
paper solves two related problems. The first bounds the number of random graphs
required in a union before its expected algebraic connectivity exceeds the
minimum needed for connectedness. The second bounds the probability that a
union of random graphs is connected. The random graph model used is the
Erd\H{o}s-R\'enyi model, and, in solving these problems, we also bound the
expectation and variance of the algebraic connectivity of unions of such
graphs. Numerical results for several use cases are given to supplement the
theoretical developments made.Comment: 16 pages, 3 tables; accepted to 2017 IEEE Conference on Decision and
Control (CDC
Optical Stark Effect and Dressed Excitonic States in a Mn-doped Quantum Dot
We report on the observation of spin dependent optically dressed states and
optical Stark effect on an individual Mn spin in a semiconductor quantum dot.
The vacuum-to-exciton or the exciton-to-biexciton transitions in a Mn-doped
quantum dot are optically dressed by a strong laser field and the resulting
spectral signature is measured in photoluminescence. We demonstrate that the
energy of any spin state of a Mn atom can be independently tuned using the
optical Stark effect induced by a control laser. High resolution spectroscopy
reveals a power, polarization and detuning dependent Autler-Townes splitting of
each optical transition of the Mn-doped quantum dot. This experiment
demonstrates a complete optical resonant control of the exciton-Mn system
Contribution to the knowledge of the Cicindelidae of Benin with collecting notes (Coleoptera Cicindelidae)
A checklist of Coleoptera Cicindelidae presently known from Benin is given. Nine taxa are recorded for the first time from this country. Collecting data, habitat and behaviour observations of adults made by the first author during two expeditions are given along with collecting data provided by the second author
Are aerobic fitness and repeated sprint ability linked to fatigue in professional soccer match-play? A pilot study
This investigation examined the association between aerobic fitness and repeated sprint ability and match-related fatigue in 9 professional outfield soccer players. Aerobic fitness using maximal aerobic speed (MAS) was determined via a continuous progressive incremental running test conducted on a motorised treadmill. A repeated sprint ability test (6 successive 6 s sprints separated by 20 s passive recovery) was performed on a non-motorised treadmill to determine mean and best sprint times and a percentage decrement score (%PD). A total of 114 observations of physical performance derived using computerised time motion analyses were collected from 33 matches. Correlations between fitness test and match-play measures were examined for 1) accumulated fatigue: percentage difference between halves for total distance covered per minute, distance run at high-intensities (HIR, actions for 1s duration, >19.1 km/h) per minute, mean recovery time between high-intensity runs, and percentage difference between the distance covered in HIR in the first 5- and 15-minute periods versus the final 5- and 15-minute periods respectively in normal time; and for 2) transient fatigue: percentage difference between the distance covered in HIR in a peak 5-minute period and the subsequent 5-minute period and for the latter compared to the mean for all other 5-minute periods. No significant relationships were observed between MAS and fatigue scores (magnitude of associations: trivial to large). For mean and best sprint times and %PD, the only reported significant correlation (r=0.77, magnitude of association: very large, p<0.05) was between %PD and the % difference across halves for mean recovery time between high-intensity runs (magnitude of other associations: small to large). Criterion measures from tests of aerobic fitness and repeated sprint ability might not accurately depict a player’s capacity to resist fatigue during professional soccer competition
Squad management, injury and match performance in a professional soccer team over a Championship-winning season
Squad management, injury and physical, tactical and technical match performance were investigated in a professional soccer team across five consecutive league seasons (2008–2013, 190 league games) with specific focus on a championship-winning season (2010/11). For each player, match participation and time-loss injuries were recorded, the latter prospectively diagnosed by the team's physician. Defending and attacking tactical and technical performance indicators investigated included ball possession and possession in opponents' half, passes, forward passes, completed passes and forward passes, crosses and completed crosses, goal attempts and goal attempts on target, successful final third entries, free-kicks and 50/50 duels won/lost. Physical performance measures included total distance and distance covered at high-speeds (≥19.1 km/h). Results showed that during the 2010/11 season, squad utilisation was lowest potentially owing to the observed lower match injury occurrence and working days lost to injury thereby increasing player availability. In 2010/11, the team won both its highest number of points and conceded its lowest number of goals especially over the second half of this season. The team also won its highest number of games directly via a goal from a substitute and scored and conceded a goal first on the highest and lowest number of occasions, respectively. While multivariate analysis of variance (MANOVA) detected a significant difference in some attacking and defensive performance indicators across the five seasons, these were generally not distinguishing factors in 2010/11. Similarly, univariate ANOVAs showed a significant difference in running distances covered across seasons, but the trend was for less activity in 2010/11
Secoviridae: a proposed family of plant viruses within the order Picornavirales that combines the families Sequiviridae and Comoviridae, the unassigned genera Cheravirus and Sadwavirus, and the proposed genus Torradovirus
The order Picornavirales includes several plant viruses that are currently classified into the families Comoviridae (genera Comovirus, Fabavirus and Nepovirus) and Sequiviridae (genera Sequivirus and Waikavirus) and into the unassigned genera Cheravirus and Sadwavirus. These viruses share properties in common with other picornavirales (particle structure, positive-strand RNA genome with a polyprotein expression strategy, a common replication block including type III helicase, a 3C-like cysteine proteinase and type I RNA-dependent RNA polymerase). However, they also share unique properties that distinguish them from other picornavirales. They infect plants and use specialized proteins or protein domains to move through their host. In phylogenetic analysis based on their replication proteins, these viruses form a separate distinct lineage within the picornavirales branch. To recognize these common properties at the taxonomic level, we propose to create a new family termed “Secoviridae” to include the genera Comovirus, Fabavirus, Nepovirus, Cheravirus, Sadwavirus, Sequivirus and Waikavirus. Two newly discovered plant viruses share common properties with members of the proposed family Secoviridae but have distinct specific genomic organizations. In phylogenetic reconstructions, they form a separate sub-branch within the Secoviridae lineage. We propose to create a new genus termed Torradovirus (type species, Tomato torrado virus) and to assign this genus to the proposed family Secoviridae
NP-hardness of decoding quantum error-correction codes
Though the theory of quantum error correction is intimately related to the
classical coding theory, in particular, one can construct quantum error
correction codes (QECCs) from classical codes with the dual containing
property, this does not necessarily imply that the computational complexity of
decoding QECCs is the same as their classical counterparts. Instead, decoding
QECCs can be very much different from decoding classical codes due to the
degeneracy property. Intuitively, one expect degeneracy would simplify the
decoding since two different errors might not and need not be distinguished in
order to correct them. However, we show that general quantum decoding problem
is NP-hard regardless of the quantum codes being degenerate or non-degenerate.
This finding implies that no considerably fast decoding algorithm exists for
the general quantum decoding problems, and suggests the existence of a quantum
cryptosystem based on the hardness of decoding QECCs.Comment: 5 pages, no figure. Final version for publicatio
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