650 research outputs found
Relationship of milk expected progeny differences (EPD\u27s)to milk production and calf weaning weight
Spring-calving Angus (n=37) and Simmental (n=28) cows were used to evaluate the relationship between milk expected progeny difference (EPD), milk production, total milk energy, and weaning weight. There were positive correlations between milk EPD\u27s and milk produced during lactation, total milk energy per lactation, and calf weaning weight. On average, a 1 lb increase in milk EPD predicted a 1.8 lb increase in calf weaning weight and an increase of 56.6 (Angus) and 70.2 (Simmental) lb in total milk per lactation. Our results suggest that producers can use milk EPD\u27s as selection tools to influence the milk production of their cows and subsequent weaning weights of their calves
Intertidal invertebrate harvesting: a meta-analysis of impacts and recovery in an important waterbird prey resource
Harvesting of marine invertebrates in intertidal areas often comes into conflict with conservation objectives for waterbird populations of the orders Anseriformes and Charadriiformes. We present a meta-analysis of the relationships between benthic invertebrate communities and various sources of intertidal harvesting disturbance to investigate impacts and recovery in bird prey resources. The effect size (Hedges’ d) of harvesting on benthic species abundance, diversity and biomass was calculated for 38 studies in various locations globally, derived from 16 publications captured through a systematic review process that met the meta-analysis inclusion criteria. A negative response to harvesting disturbance was found for all taxa, including both target and non-target species, that represent important types of waterbird prey. Impacts appear most severe from hand-gathering, which significantly reduces the abundance of target polychaete species, a key prey group for many bird species. Across all gear types, non-target species demonstrate a larger reduction in abundance compared to target species. Recovery trends vary, with differences observed between taxonomic groups and gear/habitat combinations. Abundance of bivalve molluscs, a potentially highly profitable bird prey item, is suppressed for >60 d by mechanical dredging in intertidal mud, while annelid and crustacean abundances demonstrate near recovery over the same period. Data suggest that recovery following harvesting in sandier habitats may in some cases take as long as or longer than in muddy sediments. We recommend management measures to minimise disturbance to benthic prey resources and support conservation objectives for waterbird populations to meet international legal requirements
The Recent Cholera Outbreak in the South Mrican Gold Mining Industry
A large-scale cholera surveillance programme was introduced in South Africa in November 1973 as a result of the progressive southward spread of cholera in Africa. Moore's technique for the isolation of Salmonella paratyphi was modified for cholera detection. The method proved to be very sensitive and it was possible to detect Vibrio cholerae in main sewer lines after its casual and transient introduction by an unidentified carrier. Transmission occurred in the acc!im<:tisation centre, probably through the drinking of water contaminated after it had been drawn from the tap. Faecal contamination of the environment was demonstrated, and V. cho/erae was isolated from the floor, onto which it had been disseminated from the perianal region by means of profuse perspiration. Perpetuation of cholera was probably aided by a faecally contaminated air-humidifying water reservoir, the water of which experimentally allows survival and multiplication of V. cholerae for a week and longer. Prophylactic treatment of selected high-risk groups of people was administered in the form of doxycycline, which appeared to result in rapid termination of the epidemic. Mass vaccination of all mine personnel (20 000) was carried out to reduce the incidence of clinical cholera and the bacterial load
An Algorithm for Probabilistic Alternating Simulation
In probabilistic game structures, probabilistic alternating simulation
(PA-simulation) relations preserve formulas defined in probabilistic
alternating-time temporal logic with respect to the behaviour of a subset of
players. We propose a partition based algorithm for computing the largest
PA-simulation, which is to our knowledge the first such algorithm that works in
polynomial time, by extending the generalised coarsest partition problem (GCPP)
in a game-based setting with mixed strategies. The algorithm has higher
complexities than those in the literature for non-probabilistic simulation and
probabilistic simulation without mixed actions, but slightly improves the
existing result for computing probabilistic simulation with respect to mixed
actions.Comment: We've fixed a problem in the SOFSEM'12 conference versio
Finding optimal strategies for minimum-error quantum-state discrimination
We propose a numerical algorithm for finding optimal measurements for
quantum-state discrimination. The theory of the semidefinite programming
provides a simple check of the optimality of the numerically obtained results.Comment: 4 pages, 2 figure
Does the Red Queen reign in the kingdom of digital organisms?
In competition experiments between two RNA viruses of equal or almost equal
fitness, often both strains gain in fitness before one eventually excludes the
other. This observation has been linked to the Red Queen effect, which
describes a situation in which organisms have to constantly adapt just to keep
their status quo. I carried out experiments with digital organisms
(self-replicating computer programs) in order to clarify how the competing
strains' location in fitness space influences the Red-Queen effect. I found
that gains in fitness during competition were prevalent for organisms that were
taken from the base of a fitness peak, but absent or rare for organisms that
were taken from the top of a peak or from a considerable distance away from the
nearest peak. In the latter two cases, either neutral drift and loss of the
fittest mutants or the waiting time to the first beneficial mutation were more
important factors. Moreover, I found that the Red-Queen dynamic in general led
to faster exclusion than the other two mechanisms.Comment: 10 pages, 5 eps figure
Algorithms for Game Metrics
Simulation and bisimulation metrics for stochastic systems provide a
quantitative generalization of the classical simulation and bisimulation
relations. These metrics capture the similarity of states with respect to
quantitative specifications written in the quantitative {\mu}-calculus and
related probabilistic logics. We first show that the metrics provide a bound
for the difference in long-run average and discounted average behavior across
states, indicating that the metrics can be used both in system verification,
and in performance evaluation. For turn-based games and MDPs, we provide a
polynomial-time algorithm for the computation of the one-step metric distance
between states. The algorithm is based on linear programming; it improves on
the previous known exponential-time algorithm based on a reduction to the
theory of reals. We then present PSPACE algorithms for both the decision
problem and the problem of approximating the metric distance between two
states, matching the best known algorithms for Markov chains. For the
bisimulation kernel of the metric our algorithm works in time O(n^4) for both
turn-based games and MDPs; improving the previously best known O(n^9\cdot
log(n)) time algorithm for MDPs. For a concurrent game G, we show that
computing the exact distance between states is at least as hard as computing
the value of concurrent reachability games and the square-root-sum problem in
computational geometry. We show that checking whether the metric distance is
bounded by a rational r, can be done via a reduction to the theory of real
closed fields, involving a formula with three quantifier alternations, yielding
O(|G|^O(|G|^5)) time complexity, improving the previously known reduction,
which yielded O(|G|^O(|G|^7)) time complexity. These algorithms can be iterated
to approximate the metrics using binary search.Comment: 27 pages. Full version of the paper accepted at FSTTCS 200
Life after charge noise: recent results with transmon qubits
We review the main theoretical and experimental results for the transmon, a
superconducting charge qubit derived from the Cooper pair box. The increased
ratio of the Josephson to charging energy results in an exponential suppression
of the transmon's sensitivity to 1/f charge noise. This has been observed
experimentally and yields homogeneous broadening, negligible pure dephasing,
and long coherence times of up to 3 microseconds. Anharmonicity of the energy
spectrum is required for qubit operation, and has been proven to be sufficient
in transmon devices. Transmons have been implemented in a wide array of
experiments, demonstrating consistent and reproducible results in very good
agreement with theory.Comment: 6 pages, 4 figures. Review article, accepted for publication in
Quantum Inf. Pro
Electromigration-Induced Flow of Islands and Voids on the Cu(001) Surface
Electromigration-induced flow of islands and voids on the Cu(001) surface is
studied at the atomic scale. The basic drift mechanisms are identified using a
complete set of energy barriers for adatom hopping on the Cu(001) surface,
combined with kinetic Monte Carlo simulations. The energy barriers are
calculated by the embedded atom method, and parameterized using a simple model.
The dependence of the flow on the temperature, the size of the clusters, and
the strength of the applied field is obtained. For both islands and voids it is
found that edge diffusion is the dominant mass-transport mechanism. The rate
limiting steps are identified. For both islands and voids they involve
detachment of atoms from corners into the adjacent edge. The energy barriers
for these moves are found to be in good agreement with the activation energy
for island/void drift obtained from Arrhenius analysis of the simulation
results. The relevance of the results to other FCC(001) metal surfaces and
their experimental implications are discussed.Comment: 9 pages, 13 ps figure
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