31,706 research outputs found
Wireworm Control using Fodder Rape and Mustard – evaluating the use of brassica green manures for the control of wireworm (Agriotes spp.) in organic crops
In a field experiment at ADAS Pwllpeiran in 2001, brassica green manures were grown for 6 weeks and dug in before planting King Edward potatoes, to see if they suppressed wireworm in the crop. There was a trend for potatoes grown after mustard to suffer less damage from both wireworms and slugs than potatoes grown after fodder rape or no green manure, but the differences were not significant. Further trials, with longer green manuring periods, are needed to establish if there is a benefit, and whether the breakdown products of brassica green manures are toxic to wireworms
Direct to consumer advertising via the Internet, a study of hip resurfacing
With increased use of the internet for health information and direct to consumer advertising from medical companies, there is a concern about the quality of the information available for patients. The aim of this study was to examine the quality of health information on the internet for hip resurfacing. An assessment tool was designed to measure quality of information. Websites were measured on credibility of source; usability; currentness of the information; content relevance; content accuracy/completeness and disclosure/bias. Each website assessed was given a total score, based on number of scores achieved from the above categories websites were further analysed on author, geographical origin and possession of an independent credibility check. There was positive correlation between the overall score for the website and the score of each website in each assessment category. Websites by implant companies, doctors and hospitals scored poorly. Websites with an independent credibility check such as Health on the Net (HoN) scored twice the total scores of websites without. Like other internet health websites, the quality of information on hip resurfacing websites is variable. This study highlights methods by which to assess the quality of health information on the internet and advocates that patients should look for a statement of an "independent credibility check" when searching for information on hip resurfacing
Dynamics of domain walls in magnetic nanostrips
We express dynamics of domain walls in ferromagnetic nanowires in terms of
collective coordinates generalizing Thiele's steady-state results. For weak
external perturbations the dynamics is dominated by a few soft modes. The
general approach is illustrated on the example of a vortex wall relevant to
recent experiments with flat nanowires. A two-mode approximation gives a
quantitatively accurate description of both the steady viscous motion of the
wall in weak magnetic fields and its oscillatory behavior in moderately high
fields above the Walker breakdown.Comment: 4 pages, update to published versio
Life long learning in rural areas: a report to the Countryside Agency
Lifelong Learning is a broad umbrella term which includes many different kinds of provision and different forms of learning. At its heart is formal learning, often classroom based, or involving paper and electronic media, undertaken within educational institutions such as colleges and universities. It may or may not lead to an award and it includes learning undertaken for vocational reasons as well as for general interest. It encompasses what are sometimes also known as adult education, continuing education, continuing professional development (cpd), vocational training and the acquisition of basic skills. It may also include work-based learning, and may overlap with post compulsory (post 16) education, i.e. with further education and higher education, but normally applies to all ‘adult learning’ i.e. by people over the age of 19, in particular those who are returning to study after completing their initial education.
From the perspective of the individual learner, however, non-formal learning (organised, systematic study carried on outside the framework of the formal system) is also important. This forms a continuum with informal learning that occurs frequently in the process of daily living, sometimes coincidentally for example through information media or through interpretive provision (such as at museums or heritage sites ).
This report focuses on those aspects of adult learning which are directly affected by government policies, and thus of prime concern for rural proofing
Josephson charge-phase qubit with radio frequency readout: coupling and decoherence
The charge-phase Josephson qubit based on a superconducting single charge
transistor inserted in a low-inductance superconducting loop is considered. The
loop is inductively coupled to a radio-frequency driven tank circuit enabling
the readout of the qubit states by measuring the effective Josephson inductance
of the transistor. The effect of qubit dephasing and relaxation due to electric
and magnetic control lines as well as the measuring system is evaluated.
Recommendations for operation of the qubit in magic points producing minimum
decoherence are given.Comment: 11 pages incl. 6 fig
A Short Counterexample Property for Safety and Liveness Verification of Fault-tolerant Distributed Algorithms
Distributed algorithms have many mission-critical applications ranging from
embedded systems and replicated databases to cloud computing. Due to
asynchronous communication, process faults, or network failures, these
algorithms are difficult to design and verify. Many algorithms achieve fault
tolerance by using threshold guards that, for instance, ensure that a process
waits until it has received an acknowledgment from a majority of its peers.
Consequently, domain-specific languages for fault-tolerant distributed systems
offer language support for threshold guards.
We introduce an automated method for model checking of safety and liveness of
threshold-guarded distributed algorithms in systems where the number of
processes and the fraction of faulty processes are parameters. Our method is
based on a short counterexample property: if a distributed algorithm violates a
temporal specification (in a fragment of LTL), then there is a counterexample
whose length is bounded and independent of the parameters. We prove this
property by (i) characterizing executions depending on the structure of the
temporal formula, and (ii) using commutativity of transitions to accelerate and
shorten executions. We extended the ByMC toolset (Byzantine Model Checker) with
our technique, and verified liveness and safety of 10 prominent fault-tolerant
distributed algorithms, most of which were out of reach for existing
techniques.Comment: 16 pages, 11 pages appendi
Energetic Impact of Jet Inflated Cocoons in Relaxed Galaxy Clusters
Jets from active galactic nuclei (AGN) in the cores of galaxy clusters have
the potential to be a major contributor to the energy budget of the
intracluster medium (ICM). To study the dependence of the interaction between
the AGN jets and the ICM on the parameters of the jets themselves, we present a
parameter survey of two-dimensional (axisymmetric) ideal hydrodynamic models of
back-to-back jets injected into a cluster atmosphere (with varying Mach numbers
and kinetic luminosities). We follow the passive evolution of the resulting
structures for several times longer than the active lifetime of the jet. The
simulations fall into roughly two classes, cocoon-bounded and non-cocoon
bounded sources. We suggest a correspondence between these two classes and the
Faranoff-Riley types. We find that the cocoon-bounded sources inject
significantly more entropy into the core regions of the ICM atmosphere, even
though the efficiency with which energy is thermalized is independent of the
morphological class. In all cases, a large fraction (50--80%) of the energy
injected by the jet ends up as gravitational potential energy due to the
expansion of the atmosphere.Comment: 12 pages, Accepted for publication in Ap
Dynamic Black-Level Correction and Artifact Flagging in the Kepler Data Pipeline
Instrument-induced artifacts in the raw Kepler pixel data include time-varying crosstalk from the fine guidance sensor (FGS) clock signals, manifestations of drifting moir pattern as locally correlated nonstationary noise and rolling bands in the images which find their way into the calibrated pixel time series and ultimately into the calibrated target flux time series. Using a combination of raw science pixel data, full frame images, reverse-clocked pixel data and ancillary temperature data the Keplerpipeline models and removes the FGS crosstalk artifacts by dynamically adjusting the black level correction. By examining the residuals to the model fits, the pipeline detects and flags spatial regions and time intervals of strong time-varying blacklevel (rolling bands ) on a per row per cadence basis. These flags are made available to downstream users of the data since the uncorrected rolling band artifacts could complicate processing or lead to misinterpretation of instrument behavior as stellar. This model fitting and artifact flagging is performed within the new stand-alone pipeline model called Dynablack. We discuss the implementation of Dynablack in the Kepler data pipeline and present results regarding the improvement in calibrated pixels and the expected improvement in cotrending performances as a result of including FGS corrections in the calibration. We also discuss the effectiveness of the rolling band flagging for downstream users and illustrate with some affected light curves
Computational and Experimental Investigation of Flow Around a 3-1 Prolate Spheroid
The flow around a 3-1 prolate spheroid near the critical
Reynolds number is investigated experimentally and numerically.
This work was conducted as part of a larger project to
examine the flow around Unmanned Underwater Vehicles. The
experimental investigation has been performed in a water tunnel
at the Australian Maritime College. Fast response pressure
probes and a 3-D automated traverse have been developed to
investigate the state of the boundary layer. A commercial CFD
code has been modified to allow the experimentally determined
boundary layer state to be included in the computation. Qualitative
and quantitative comparisons between the measured and
calculated results are discussed. The tests on the spheroid were
conducted within a Reynolds numbers range of 0 .6 ×106 to
4×106. The results presented here are for an incidence of 10
Using Flow Specifications of Parameterized Cache Coherence Protocols for Verifying Deadlock Freedom
We consider the problem of verifying deadlock freedom for symmetric cache
coherence protocols. In particular, we focus on a specific form of deadlock
which is useful for the cache coherence protocol domain and consistent with the
internal definition of deadlock in the Murphi model checker: we refer to this
deadlock as a system- wide deadlock (s-deadlock). In s-deadlock, the entire
system gets blocked and is unable to make any transition. Cache coherence
protocols consist of N symmetric cache agents, where N is an unbounded
parameter; thus the verification of s-deadlock freedom is naturally a
parameterized verification problem. Parametrized verification techniques work
by using sound abstractions to reduce the unbounded model to a bounded model.
Efficient abstractions which work well for industrial scale protocols typically
bound the model by replacing the state of most of the agents by an abstract
environment, while keeping just one or two agents as is. However, leveraging
such efficient abstractions becomes a challenge for s-deadlock: a violation of
s-deadlock is a state in which the transitions of all of the unbounded number
of agents cannot occur and so a simple abstraction like the one above will not
preserve this violation. In this work we address this challenge by presenting a
technique which leverages high-level information about the protocols, in the
form of message sequence dia- grams referred to as flows, for constructing
invariants that are collectively stronger than s-deadlock. Efficient
abstractions can be constructed to verify these invariants. We successfully
verify the German and Flash protocols using our technique
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