Detection of Optical Synchrotron Emission from the Radio Jet of 3C279

We report the detection of optical and ultraviolet emission from the kiloparsec scale jet of the well-known quasar 3C~279. A bright knot, discovered in archival V and U band {\it Hubble Space Telescope} Faint Object Camera images, is coincident with a peak in the radio jet \sim0.6\arcsec from the nucleus. The detection was also confirmed in Wide Field Planetary Camera-2 images. Archival Very Large Array and MERLIN radio data are also analyzed which help to show that the high-energy optical/UV continuum, and spectrum, are consistent with a synchrotron origin from the same population of relativistic electrons responsible for the radio emission.Comment: 6 pages, 3 figs. accepted for publication in ApJL with minor revision

Open-source development experiences in scientific software: the HANDE quantum Monte Carlo project

The HANDE quantum Monte Carlo project offers accessible stochastic algorithms for general use for scientists in the field of quantum chemistry. HANDE is an ambitious and general high-performance code developed by a geographically-dispersed team with a variety of backgrounds in computational science. In the course of preparing a public, open-source release, we have taken this opportunity to step back and look at what we have done and what we hope to do in the future. We pay particular attention to development processes, the approach taken to train students joining the project, and how a flat hierarchical structure aids communicationComment: 6 pages. Submission to WSSSPE

Accurate exchange-correlation energies for the warm dense electron gas

Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the $k$-space configuration path-integral formalism disagree by up to $\sim$$10$\% at certain reduced temperatures $T/T_F \le 0.5$ and densities $r_s \le 1$. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that DMQMC can calculate free energies directly and present exact free energies for $T/T_F \ge 1$ and $r_s \le 2$.Comment: Accepted version: added free energy data and restructured text. Now includes supplementary materia

Storyline description of Southern Hemisphere midlatitude circulation and precipitation response to greenhouse gas forcing

As evidence of climate change strengthens, knowledge of its regional implications becomes an urgent need for decision making. Current understanding of regional precipitation changes is substantially limited by our understanding of the atmospheric circulation response to climate change, which to a high degree remains uncertain. This uncertainty is reflected in the wide spread in atmospheric circulation changes projected in multimodel ensembles, which cannot be directly interpreted in a probabilistic sense. The uncertainty can instead be represented by studying a discrete set of physically plausible storylines of atmospheric circulation changes. By mining CMIP5 model output, here we take this broader perspective and develop storylines for Southern Hemisphere (SH) midlatitude circulation changes, conditioned on the degree of global-mean warming, based on the climate responses of two remote drivers: the enhanced warming of the tropical upper troposphere and the strengthening of the stratospheric polar vortex. For the three continental domains in the SH, we analyse the precipitation changes under each storyline. To allow comparison with previous studies, we also link both circulation and precipitation changes with those of the Southern Annular Mode. Our results show that the response to tropical warming leads to a strengthening of the midlatitude westerly winds, whilst the response to a delayed breakdown (for DJF) or strengthening (for JJA) of the stratospheric vortex leads to a poleward shift of the westerly winds and the storm tracks. However, the circulation response is not zonally symmetric and the regional precipitation storylines for South America, South Africa, South Australia and New Zealand exhibit quite specific dependencies on the two remote drivers, which are not well represented by changes in the Southern Annular Mode

INSPECTION AND MAINTENANCE EXPERIENCE WITH HRE-2

Experience in replacement of highly radioactive components of Homogeneous Reactor Experiment No. 2 is discussed, with particular emphasis on containment of air-bonne contamination and control of personnel exposure. The design and operation of tools and viewing devices developed to observe the hole in the HRE-2 core tank are described. (auth

DASI First Results: A Measurement of the Cosmic Microwave Background Angular Power Spectrum

We present measurements of anisotropy in the Cosmic Microwave Background (CMB) from the first season of observations with the Degree Angular Scale Interferometer (DASI). The instrument was deployed at the South Pole in the austral summer 1999--2000, and made observations throughout the following austral winter. We have measured the angular power spectrum of the CMB in the range 100<l<900 with high signal-to-noise. In this paper we review the formalism used in the analysis, in particular the use of constraint matrices to project out contaminants such as ground and point source signals, and to test for correlations with diffuse foreground templates. We find no evidence of foregrounds other than point sources in the data, and find a maximum likelihood temperature spectral index beta = -0.1 +/- 0.2 (1 sigma), consistent with CMB. We detect a first peak in the power spectrum at l approx 200, in agreement with previous experiments. In addition, we detect a peak in the power spectrum at l approx 550 and power of similar magnitude at l approx 800 which are consistent with the second and third harmonic peaks predicted by adiabatic inflationary cosmological models.Comment: 8 pages, 1 figure, minor changes in response to referee comment

A study of the usefulness of Skylab EREP data for earth resources studies in Australia

The author has identified the following significant results. In subhumid, vegetated areas, S190B photography: (1) has a potentially operational role in detecting lineaments in 1:100,000 scale geological mapping and in major civil engineering surveys; (2) is of limited value for regional lithological mapping at 1:500,000 scale; and (3) provided much useful synoptic information and some detailed information of direct value to the mapping of nonmineral natural resources such as vegetation, land soil, and water. In arid, well exposed areas, S190B photography could be used: (1) with a limited amount of field traverses, to produce reliable 1:500,000 scale geological maps of sedimentary sequences; (2) to update superficial geology on 1:250,000 scale maps; and (3) together with the necessary field studies, to prepare landform, soil, and vegetation maps at 1:1,000,000 scale. Skylab photography was found to be more useful than LANDSAT images for small scale mapping of geology and land types, and for the revision of topographic maps at 1:100,000 scale, because of superior spatial resolution and stereoscopic coverage

A quasi-periodic oscillation in the blazar J1359+4011

The OVRO 40-m telescope has been monitoring the 15 GHz radio flux density of over 1200 blazars since 2008. The 15 GHz light curve of the flat spectrum radio quasar J1359+4011 shows a strong and persistent quasi-periodic oscillation. The time-scale of the oscillation varies between 120 and 150 days over a $\sim4$ year time span. We interpret this as the active galactic nucleus mass-scaled analog of low-frequency quasi-periodic oscillations from Galactic microquasars, or as evidence of modulation of the accretion flow by thermal instabilites in the "inner" accretion disc.Comment: 4 pages, 2 figures, 1 table. Accepted for publication in MNRAS Letter