| geographic components of linkage disequilibrium in natural populations of escherichia coli. | geographic variation in the genetic structure of natural enteric populations of escherichia coli was assessed at both the single-locus and dilocus levels from allozyme genotypes at 12 enzyme loci in 178 cell lines isolated from human hosts in sweden, iowa, and tonga. although there was significant heterogeneity in allele frequencies at six of the 12 loci, geographic variation accounted for only 2.0% of the total genetic diversity (ht = 0.518). ohta's d-statistics were used to partition the total ... | 1983 | 6400648 |
| the availability of state-level data on interstate cattle movements in the united states. | knowledge about the patterns of animal movement--particularly feeder-cattle movement--within the usa is necessary in order to anticipate how diseases might be spread geographically. this study was conducted to explore the availability of interstate-level movement data which might be used to develop a more coherent national picture of interstate feeder-cattle movement. state statistical offices of the national agricultural statistics service, 1996 (nass) and departments of agriculture in all 50 s ... | 1998 | 9879593 |
| potential oversummering and overwintering regions for the wheat stripe rust pathogen in the contiguous united states. | epidemics of wheat stripe rust, caused by puccinia striiformis f. sp. tritici (pst), are more frequent in the regions where pst can oversummer and overwinter. regions for potential oversummering and overwintering of pst were determined in the contiguous united states using a survival index (si) ranging from 0 (most unfavorable) to 10 (most favorable) developed based on long-term weather data. the pathogen can survive in cool summer in the most regions north of latitude 40°n, particularly washing ... | 2014 | 23722926 |