Sequence organization of feline leukemis virus DNA in infected cells

A restriction site map has been deduced of unintegrated and integrated FeLV viral DNA found in human RD cells after experimental infection with the Gardner-Arnstein strain of FeLV. Restriction fragments were ordered by single and double enzyme digests followed by Southern transfer (1) and hybridization with 32P-labeled viral cDNA probes. The restriction map was oriented with respect to the 5' and 3' ends of viral RNA by using a 3' specific hybridization probe. The major form of unintegrated viral DNA found was a 8.7 kb linear DNA molecule bearing a 450 bp direct long terminal redundancy (LTR) derived from both 5' and 3' viral RNA sequences. Minor, circular forms, 8.7 kb and 8.2 kb in length were also detected, the larger one probably containing two adjacent copies of the LTR and the smaller one containing one copy of the LTR. Integrated copies of FeLV are colinear with the unintegrated linear form and contain the KpnI and SmaI sites found in each LTR

Cancer rates over age, time, and place: insights from stochastic models of heterogeneous populations

Individuals at the same age in the same population differ along numerous risk factors that affect their chances of various causes of death. The frail and susceptible tend to die first. This differential selection may partially account for some of the puzzles in cancer epidemiology, including the lack of apparent progress in reducing cancer incidence and mortality rates over time. (AUTHORS)

Archaea produce lower yields of N2O than bacteria during aerobic ammonia oxidation in soil

Acknowledgments The authors are members of the Nitrous Oxide Research Alliance (NORA), a Marie Skłodowska-Curie ITN and research project under the EU's seventh framework program (FP7). GN is funded by the AXA Research Fund. The authors would like to thank Dr Nicholas Morley for assistance with gas chromatography, Dr Robin Walker and the SRUC Craibstone Estate (Aberdeen) for access to the agricultural plots and Dr Thomas Cornulier for statistical advice.Peer reviewedPublisher PD

Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: analytical results in the regime of ground-state cooling

We show that in the regime of ground-state cooling, simple expressions can be derived for the performance of resolved-sideband cooling --- an example of coherent feedback control --- and optimal linear measurement-based feedback cooling for a harmonic oscillator. These results are valid to leading order in the small parameters that define this regime. They provide insight into the origins of the limitations of coherent and measurement-based feedback for linear systems, and the relationship between them. These limitations are not fundamental bounds imposed by quantum mechanics, but are due to the fact that both cooling methods are restricted to use only a linear interaction with the resonator. We compare the performance of the two methods on an equal footing --- that is, for the same interaction strength --- and confirm that coherent feedback is able to make much better use of the linear interaction than measurement-based feedback. We find that this performance gap is caused not by the back-action noise of the measurement but by the projection noise. We also obtain simple expressions for the maximal cooling that can be obtained by both methods in this regime, optimized over the interaction strength.Comment: 14 pages, 2 png figures; v2: revised for publicatio