167 research outputs found
On-Farm Benchmarking: How to Do It and How to Do It Better
Benchmarking is the practice of establishing the relative performance of a business or enterprise against an appropriate standard, generally industry standards derived from a survey of farms. The Policy Commission into the Future of Farming and Food (2002) highlighted a need to spread and improve benchmarking on farms. The requirements of effective benchmarking are illustrated in a ten step framework. The ten steps illustrate the range of expertise and resources a manager requires before being able to justify allocating resources to benchmarking. A comparison of alternative farm surveys and methodologies used to collect, analyse and report industry standards illustrates the difficulties farmers can have in identifying appropriate, robust and accurate industry standards. It is concluded that there needs to be a thorough rationalisation of farm surveys and agreement on methodologies to make benchmarking more effective and more efficient.benchmarking, comparative analysis, processes, industry standards, methodology, techniques, Farm Management,
Uptake of Sexed Semen by UK Suckler Beef Producers
Dairy farmers have been able to use sexed semen from dairy breeds to pre-determine the sex of calves since 2000, sexed semen from beef bulls is not currently commercially available, but is expected within 2 years. A survey of a stratified random sample of suckler cow farmers is used to identify the potential uptake of sexed semen when it becomes available using a logistic limited dependent variable model to identify different characteristics between farmers who intend to use sexed semen and those who do not. Herd size, the perception of the quality of bulls used to produce sexed semen, anticipated problems using AI, concern over conception rates, the cost and profitability of using sexed semen and herd replacement policy are found to be the major factors that will influence uptake. The relative importance of each constraint is shown, and approaches to reduce these constraints discussed.herd replacements, sexed semen, suckler beef production, subsidies, technical innovation, Livestock Production/Industries,
Mathematical modelling of contact dermatitis from nickel and chromium
Dermal exposure to metal allergens can lead to irritant (ICD) and allergic contact dermatitis
(ACD). In this paper we present a mathematical model of the absorption of metal ions, hexavalent
chromium and nickel, into the viable epidermis and compare the localised irritant and T-lymphocyte
(T-cell) mediated immune responses. The model accounts for the spatial-temporal variation of skin
health, extra and intracellular allergen concentrations, innate immune cells, T-cells, cytokine signalling and lymph node activity up to about 6 days after contact with these metals; repair processes
associated with withdrawal of exposure to both metals is not considered in the current model, being
assumed secondary during the initial phases of exposure. Simulations of the resulting system of PDEs
are studied in one-dimension, i.e. across skin depth, and three-dimensional scenarios with the aim of
comparing the responses to the two ions in the cases of first contact (no T-cells initially present) and
second contact (T-cells initially present). The results show that on continuous contact, chromium ions
elicit stronger skin inflammation, but for nickel, subsequent re-exposure stimulates stronger responses
due to an accumulation of cytotoxic T-cell mediated responses which characterise ACD. Furthermore,
the surface area of contact to these metals has little effect on the speed of response, whilst sensitivity
is predicted to increase with the thickness of skin. The modelling approach is generic and should be
applicable to describe contact dermatitis from a wide range of allergens
Signal and System Approximation from General Measurements
In this paper we analyze the behavior of system approximation processes for
stable linear time-invariant (LTI) systems and signals in the Paley-Wiener
space PW_\pi^1. We consider approximation processes, where the input signal is
not directly used to generate the system output, but instead a sequence of
numbers is used that is generated from the input signal by measurement
functionals. We consider classical sampling which corresponds to a pointwise
evaluation of the signal, as well as several more general measurement
functionals. We show that a stable system approximation is not possible for
pointwise sampling, because there exist signals and systems such that the
approximation process diverges. This remains true even with oversampling.
However, if more general measurement functionals are considered, a stable
approximation is possible if oversampling is used. Further, we show that
without oversampling we have divergence for a large class of practically
relevant measurement procedures.Comment: This paper will be published as part of the book "New Perspectives on
Approximation and Sampling Theory - Festschrift in honor of Paul Butzer's
85th birthday" in the Applied and Numerical Harmonic Analysis Series,
Birkhauser (Springer-Verlag). Parts of this work have been presented at the
IEEE International Conference on Acoustics, Speech, and Signal Processing
2014 (ICASSP 2014
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