Associations between sole ulcer, white line disease and digital dermatitis and the milk yield of 1824 dairy cows on 30 dairy cow farms in England and Wales from February 2003–November 2004

The milk yields of 1824 cows were used to investigate the effect of lesion-specific causes of lameness, based on farmer treatment and diagnosis of lame cows, on milk yield. A three level hierarchical model of repeated test day yields within cows within herds was used to investigate the impact of lesion-specific causes of lameness (sole ulcer, white line disease, digital dermatitis and other causes) on milk yield before and after treatment compared with unaffected cows. Cattle which developed sole ulcer (SU) and white line disease (WLD) were higher yielding cattle before they were diagnosed. Their milk production fell to below that of the mean of unaffected cows before diagnosis and remained low after diagnosis. In cattle which developed digital dermatitis (DD) there was no significant difference in milk yield before treatment and a slightly raised milk yield immediately after treatment. The estimated milk loss attributable to SU and WLD was approximately 570kg and 370kg respectively. These results highlight that specific types of lameness vary by herds and within herds they are associated with higher yielding cattle. Consequently lesion-specific lameness reduction programmes targeting the cow and farm specific causes of lameness might be more effective than generic recommendations. They also highlight the importance of milk loss when estimating the economic impact of SU and WLD on the farms profitability

Almost Block Diagonal Linear Systems: Sequential and Parallel Solution Techniques, and Applications

Almost block diagonal (ABD) linear systems arise in a variety of contexts, specifically in numerical methods for two-point boundary value problems for ordinary differential equations and in related partial differential equation problems. The stable, efficient sequential solution of ABDs has received much attention over the last fifteen years and the parallel solution more recently. We survey the fields of application with emphasis on how ABDs and bordered ABDs (BABDs) arise. We outline most known direct solution techniques, both sequential and parallel, and discuss the comparative efficiency of the parallel methods. Finally, we examine parallel iterative methods for solving BABD systems. Copyright (C) 2000 John Wiley & Sons, Ltd

Irrigation Management -- Water Requirements and Water Balance

This paper seeks to discuss irrigation water requirement estimates in the light of current practice, important developments during the 1970's, significant research and future research and applications of that research. Each of these are elaborated in more detail in the text of this paper. A major addition to the science and art of estimating irrigation water requirements has been to replace the often ambiguous "potential evapotranspiration" with "reference crop evapotranspiration". In the past decade a series of experiments relating irrigation water applications to crop yield now permit a much better economic analysis of the use of water for irrigation. The estimation of monthly irrigation water requirements was facilitated, particularly for varying climatic conditions with the United Nations publication "Crop Water Requirements" by Doorenbos and Pruitt (1977). Estimation of daily water requirements for purposes of irrigation scheduling has been refined by the development of an albedo model and a wind function for the Penman method, that is variable throughout the season, Wright (1981). Several western states are experiencing lawsuits or other legal deliberations involving seasonal irrigation water requirements because of conflicts between groups of water users or water right transfers from agriculture to industry or municipal use. Irrigation scheduling continues to be refined from the standpoints of predicting ET, verifying yield conditions and other factors like production and peak pumping power reduction. Future research probably will include emphasis on breeding crops that require less water, refinements on the relationships between yields and water consumption, refinements in methods of estimating irrigation water requirements, and the development of irrigation schemes that minimize water and energy requirements. For other methods and more detail the reader is referred to sources such as Doorenbos and Pruitt (1977), Jensen (1974), Barman. et al. (1981)

The ASCE neutron probe calibration study: overview

A workshop was held at Logan, Utah to gather field information on neutron probe calibration and operation. Several techniques and instruments were compared. This paper serves to establish the background information for the work and describe the overall approaches, conditions, and equipment. Other papers presented at this conference provide detailed procedures and results

Dynamic splitting of a Bose-Einstein Condensate

We study the dynamic process of splitting a condensate by raising a potential barrier in the center of a harmonic trap. We use a two-mode model to describe the phase coherence between the two halves of the condensate. Furthermore, we explicitly consider the spatial dependence of the mode funtions, which varies depending on the potential barrier. This allows to get the tunneling coupling between the two wells and the on-site energy as a function of the barrier height. Moreover we can get some insight on the collective modes which are excited by raising the barrier. We describe the internal and external degrees of freedom by variational ansatz. We distinguish the possible regimes as a function of the characteristic parameters of the problem and identify the adiabaticity conditions.Comment: 17 pages, 8 figure