Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10-7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

Formation of the first three gravitational-wave observations through isolated binary evolution.

During its first four months of taking data, Advanced LIGO has detected gravitational waves from two binary black hole mergers, GW150914 and GW151226, along with the statistically less significant binary black hole merger candidate LVT151012. Here we use the rapid binary population synthesis code COMPAS to show that all three events can be explained by a single evolutionary channel-classical isolated binary evolution via mass transfer including a common envelope phase. We show all three events could have formed in low-metallicity environments (Z=0.001) from progenitor binaries with typical total masses ≳160M⊙, ≳60M⊙ and ≳90M⊙, for GW150914, GW151226 and LVT151012, respectively.

Whole-genome enrichment and sequencing of Chlamydia trachomatis directly from clinical samples.

BACKGROUND: Chlamydia trachomatis is a pathogen of worldwide importance, causing more than 100 million cases of sexually transmitted infections annually. Whole-genome sequencing is a powerful high resolution tool that can be used to generate accurate data on bacterial population structure, phylogeography and mutations associated with antimicrobial resistance. The objective of this study was to perform whole-genome enrichment and sequencing of C. trachomatis directly from clinical samples. METHODS: C. trachomatis positive samples comprising seven vaginal swabs and three urine samples were sequenced without prior in vitro culture in addition to nine cultured C. trachomatis samples, representing different serovars. A custom capture RNA bait set, that captures all known diversity amongst C. trachomatis genomes, was used in a whole-genome enrichment step during library preparation to enrich for C. trachomatis DNA. All samples were sequenced on the MiSeq platform. RESULTS: Full length C. trachomatis genomes (>95-100% coverage of a reference genome) were successfully generated for eight of ten clinical samples and for all cultured samples. The proportion of reads mapping to C. trachomatis and the mean read depth across each genome were strongly linked to the number of bacterial copies within the original sample. Phylogenetic analysis confirmed the known population structure and the data showed potential for identification of minority variants and mutations associated with antimicrobial resistance. The sensitivity of the method was >10-fold higher than other reported methodologies. CONCLUSIONS: The combination of whole-genome enrichment and deep sequencing has proven to be a non-mutagenic approach, capturing all known variation found within C. trachomatis genomes. The method is a consistent and sensitive tool that enables rapid whole-genome sequencing of C. trachomatis directly from clinical samples and has the potential to be adapted to other pathogens with a similar clonal nature.

Socioeconomic variation in incidence of epilepsy: prospective community based study in south east England.

OBJECTIVE: To determine the incidence of epilepsy in a general practice population and its variation with socioeconomic deprivation. DESIGN: Prospective surveillance for new cases over an 18 or 24 month period. PARTICIPANTS: All patients on practice registers categorised for deprivation with the Carstairs score of their postcode. SETTING: 20 general practices in London and south east England. MAIN OUTCOME MEASURE: Confirmed diagnosis of epilepsy. RESULTS: 190 new cases of epilepsy were identified during 369 283 person years of observation (crude incidence 51.5 (95% confidence interval 44.4 to 59.3) per 100 000 per year). The incidence was 190 (138 to 262) per 100 000 in children aged 0-4 years, 30.8 (21.3 to 44.6) in those aged 45-64 years, and 58.7 (42.5 to 81.0) in those aged > or =65 years. There was no apparent difference in incidence between males and females. The incidence showed a strong association with socioeconomic deprivation, the age and sex adjusted incidence in the most deprived fifth of the study population being 2.33 (1.46 to 3.72) times that in the least deprived fifth (P=0.001 for trend across fifths). Adjustment for area (London v outside London) weakened the association with deprivation (rate ratio 1.62 (0.91 to 2.88), P=0.12 for trend). CONCLUSIONS: The incidence of epilepsy seems to increase with socioeconomic deprivation, though the association may be confounded by other factors.