2,418 research outputs found
A study of the distribution of Salmonella serovars in an integrated pig company
A total of 3220 faecal samples from 161 pig farms (rearing and finishing units) belonging to an integrated pig enterprise were collected over a period of 18 months. Salmonella was found in 630 (19.5%) of the samples. At the farm level, 111 of 161 premises (69%) had at least one Salmonella- positive sample. 72.8% of rearing units and 66.6% of finishing units were positive for Salmonella; 61.4% of isolates were S. Typhimurium (387/630 isolates), and 25% of isolates were S. Derby (157/630). S. Panama, which was the third most common serovar (4.9% of isolates), is rarely found in pigs or other animals in the UK and appeared to be largely specific to this company, being found in the multiplier herd as well
Using discrete Darboux polynomials to detect and determine preserved measures and integrals of rational maps
In this Letter we propose a systematic approach for detecting and calculating
preserved measures and integrals of a rational map. The approach is based on
the use of cofactors and Discrete Darboux Polynomials and relies on the use of
symbolic algebra tools. Given sufficient computing power, all rational
preserved integrals can be found.
We show, in two examples, how to use this method to detect and determine
preserved measures and integrals of the considered rational maps.Comment: 8 pages, 1 Figur
Trees and superintegrable Lotka-Volterra families
To any tree on vertices we associate an -dimensional Lotka-Volterra
system with parameters and prove it is superintegrable, i.e. it admits
functionally independent integrals. We also show how these systems can be
reduced to an ()-dimensional system which is superintegrable and solvable
by quadratures.Comment: 13 pages, 2 figure
Linear Darboux polynomials for Lotka-Volterra systems, trees and superintegrable families
We present a method to construct superintegrable -component Lotka-Volterra
systems with parameters. We apply the method to Lotka-Volterra systems
with components for , and present several -dimensional
superintegrable families. The Lotka-Volterra systems are in one-to-one
correspondence with trees on vertices.Comment: 14 pages, 4 figure
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