Background.Interventions to reduce under-5 mortality can either target the vulnerable or include all children regardless of state of health. Here, we assess whether mass distribution of a broad-spectrum antibiotic to pre-school children reduces mortality in sub-Saharan Africa.Methods.MORDOR was a large simple trial that randomized communities in Malawi, Niger, and Tanzania to 4 biannual mass distributions of either oral azithromycin or placebo. Children aged 1-59 months were enumerated and offered treatment. Vital status was assessed at the subsequent biannual census. The primary outcome was aggregate all-cause mortality, with country-specific rates as pre-specified subgroup analyses.Results.In total, 1533 communities were randomized, 190,238 children censused at baseline, and 323,302 person-years monitored. Mean antibiotic coverage over the 4 biannual distributions was 90.4% (SD 10.4%) of the censused population. The overall annual mortality rate in placebo- treated communities was 16.5 per 1000 person-years (9.6 per 1000 person-years in Malawi, 27.5 in Niger, and 5.5 in Tanzania). Antibiotic-treated communities had an estimated 13.5% lower mortality overall (95% CI 6.7%—19.8%, P<0.001). Mortality was 5.7% lower in Malawi (CI - 9.7%—18.9%, P=0.45), 18.1% lower in Niger (CI 10.0%—25.5%, P<0.001), and 3.4% lower in Tanzania (CI -21.2%—23.0%, P=0.77). The greatest reduction was observed in 1-5 month-old children (24.9% lower, CI 10.6%—37.0%, P=0.001).Conclusions.Mass azithromycin distribution to post-neonatal, pre-school children may reduce childhood mortality in sub-Saharan Africa, particularly in high mortality areas such as Niger. Any implementation would need to consider selection for antibiotic resistance.

We present outburst spectroscopy of GX 339-4 which may reveal the motion of its elusive companion star. N iii lines exhibit sharp emission components moving over ∼ 300 km s −1 in a single night. The most plausible interpretation of these components is that they are formed by irradiation of the companion star and the velocities indicate its orbital motion. We also detect motion of the wings of the He ii 4686Å line and changes in its morphology. No previously proposed period is consistent with periodic behavior of all of these measures. However, consistent and sensible solutions are obtained for periods around 1.7 days. For the best period, 1.7557 days, we estimate a mass function of 5.8 ± 0.5 M ⊙ . Even allowing for aliases, the 95 % confidence lower-limit on the mass function is 2.0 M ⊙ . GX 339-4 can therefore be added to the list of dynamical black hole candidates. This is supported by the small motion in the wings of the He ii line; if the compact object velocity is not larger than the observed motion then the mass ratio is q 0.08, similar to other systems harboring black holes. Finally, we note that the sharp components are not always present, but do seem to occur within a repeating phase range. This appears to migrate between our epochs of observation, and may indicate shielding of the companion star by a variable accretion geometry such as a warp.

ULTRACAM is a portable, high-speed imaging photometer designed to study faint astronomical objects at high temporal resolutions. ULTRACAM employs two dichroic beamsplitters and three frame-transfer CCD cameras to provide three-colour optical imaging at frame rates of up to 500 Hz. The instrument has been mounted on both the 4.2-m William Herschel Telescope on La Palma and the 8.2-m Very Large Telescope in Chile, and has been used to study white dwarfs, brown dwarfs, pulsars, black hole/neutron star X-ray binaries, gamma-ray bursts, cataclysmic variables, eclipsing binary stars, extrasolar planets, flare stars, ultracompact binaries, active galactic nuclei, asteroseismology and occultations by Solar System objects (Titan, Pluto and Kuiper Belt objects). In this paper we describe the scientific motivation behind ULTRACAM, present an outline of its design and report on its measured performance.

In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to γ-ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet is critically dependent on the position of the break in its spectrum, between optically thick (self-absorbed) and optically thin synchrotron emission. This break, or turnover, has been reported in just one black hole X-ray binary (BHXB) thus far, GX 339-4, and inferred via spectral fitting in two others, A0620-00 and Cyg X-1. Here, we collect a wealth of multiwavelength data from the outbursts of BHXBs during hard X-ray states, in order to search for jet breaks as yet unidentified in their spectral energy distributions. In particular, we report the direct detection of the jet break in the spectrum of V404 Cyg during its 1989 outburst, at ν b = (1.8 ± 0.3) × 10 14 Hz (1.7 ± 0.2µm). We increase the number of BHXBs with measured jet breaks from three to eight. Jet breaks are found at frequencies spanning more than two orders of magnitude, from ν b = (4.5 ± 0.8) × 10 12 Hz for XTE J1118+480 during its 2005 outburst, to ν b > 4.7 × 10 14 Hz for V4641 Sgr in outburst. A positive correlation between jet break frequency and luminosity is expected theoretically; ν b ∝ L ∼0.5 ν,jet if other parameters are constant. With constraints on the jet break in a total of 12 BHXBs including two quiescent systems, we find a large range of jet break frequencies at similar luminosities and no obvious global relation (but such a relation cannot be ruled out for individual sources). We speculate that different magnetic field strengths and/or different radii of the acceleration zone in the inner regions of the jet are likely to be responsible for the observed scatter between sources. There is evidence that the high energy cooling break in the jet spectrum shifts from UV energies at L X ∼ 10 −8 L Edd (implying the jet may dominate the Xray emission in quiescence) to X-ray energies at ∼ 10 −3 L Edd . Finally, we find that the jet break luminosity scales as L ν,jet ∝ L 0.56±0.05 X (very similar to the radio-X-ray correlation), and radio-faint BHXBs have fainter jet breaks. In quiescence the jet break luminosity exceeds the X-ray luminosity.