13 research outputs found
Genetic analysis reveals the complex structure of HIV-1 transmission within defined risk groups
We explored the epidemic history of HIV-1 subtype B in the United Kingdom using
statistical methods that infer the population history of pathogens from sampled gene
sequence data. Phylogenetic analysis of HIV-1 pol gene sequences from Britain showed
at least six large transmission chains, indicating a genetically variable, but
epidemiologically homogeneous, epidemic among men having sex with men. Through
coalescent-based analysis we showed that these chains arose through separate
introductions of subtype B strains into the United Kingdom in the early-to-mid 1980s.
After an initial period of exponential growth, the rate of spread generally slowed in the
early 1990s, which is more likely to correlate with behaviour change than with reduced
infectiousness resulting from highly active antiretroviral therapy. Our results provide new
insights into the complexity of HIV-1 epidemics that must be considered when
developing HIV monitoring and prevention initiatives
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Reducing the impact of PCR-mediated recombination in molecular evolution and environmental studies using a new-generation high-fidelity DNA polymerase
The discovery of a massive supercluster at z = 0.9 in the UKIDSS Deep eXtragalactic Survey
The definitive version is available at www.blackwell-synergy.com Copyright Blackwell Publishing DOI : 10.1111/j.1365-2966.2007.12037.xPeer reviewe