No abstract

Flow between concentric cylinders with a rotating inner cylinder is studied for Reynolds numbers in the range 2x10(3) R(T).

We investigate probability density functions of velocity differences at different distances r measured in a Couette-Taylor flow for a range of Reynolds numbers Re. There is good agreement with the predictions of a theoretical model based on nonextensive statistical mechanics (where the entropies are nonadditive for independent subsystems). We extract the scale-dependent nonextensitivity parameter q(r,Re) from the laboratory data.

Visna/Maedi, or ovine progressive pneumonia (OPP) as it is known in the United States, is an incurable slow-acting disease of sheep caused by persistent lentivirus infection. This disease affects multiple tissues, including those of the respiratory and central nervous systems. Our aim was to identify ovine genetic risk factors for lentivirus infection. Sixty-nine matched pairs of infected cases and uninfected controls were identified among 736 naturally exposed sheep older than five years of age. These pairs were used in a genome-wide association study with 50,614 markers. A single SNP was identified in the ovine transmembrane protein (TMEM154) that exceeded genome-wide significance (unadjusted p-value 3×10−9). Sanger sequencing of the ovine TMEM154 coding region identified six missense and two frameshift deletion mutations in the predicted signal peptide and extracellular domain. Two TMEM154 haplotypes encoding glutamate (E) at position 35 were associated with infection while a third haplotype with lysine (K) at position 35 was not. Haplotypes encoding full-length E35 isoforms were analyzed together as genetic risk factors in a multi-breed, matched case-control design, with 61 pairs of 4-year-old ewes. The odds of infection for ewes with one copy of a full-length TMEM154 E35 allele were 28 times greater than the odds for those without (p-value<0.0001, 95% CI 5–1,100). In a combined analysis of nine cohorts with 2,705 sheep from Nebraska, Idaho, and Iowa, the relative risk of infection was 2.85 times greater for sheep with a full-length TMEM154 E35 allele (p-value<0.0001, 95% CI 2.36–3.43). Although rare, some sheep were homozygous for TMEM154 deletion mutations and remained uninfected despite a lifetime of significant exposure. Together, these findings indicate that TMEM154 may play a central role in ovine lentivirus infection and removing sheep with the most susceptible genotypes may help eradicate OPP and protect flocks from reinfection.

Nonspecific uterine infections reduce the reproductive efficiency of cows and the profit potential of dairy farms. Fortunately, most cows do not develop severe uterine infections. The term uterine infection indicates that the uterus is contaminated with pathogenic organisms. Actinomyces pyogenes, either alone or with other bacteria, is often associated with uterine infections. When A. pyogenes was isolated from uterine fluids after d 21 postpartum, cows developed severe endometritis and were infertile at first service. However, the exact causes of uterine infections are unknown but are associated with several factors. Cows with dystocia, retained placenta, twins or still-births, and various metabolic disorders are more likely to develop metritis than are other cows. Aberrant immune function before and after calving seems to predispose cows to severe uterine infections. Few cows die from uterine infections, but cows with uterine infections are more likely to be culled for poor reproductive performance. Also, uterine infections can reduce milk production, and some treatments contaminate milk. Because they are nonspecific, uterine infections are difficult to prevent; attention to sanitation and periparturient hygiene, especially during assisted calving, may be the best defense. Evidence that aberrant immuno function predisposes cows to uterine infections indicates that methods for regulating immune function in periparturient cows have the potential for preventing or treating uterine infections.