Proton and cadmium adsorption by the archaeon Thermococcus zilligii: Generalising the contrast between thermophiles and mesophiles as sorbents

Adsorption by microorganisms can play a significant role in the fate and transport of metals in natural systems. Surface complexation models (SCMs) have been applied extensively to describe metal adsorption by mesophilic bacteria, and several recent studies have extended this framework to thermophilic bacteria. We conduct acid-base titrations and batch experiments to characterise proton and Cd adsorption onto the thermophilic archaeon Thermococcus zilligii. The experimental data and the derived SCMs indicate that the archaeon displays significantly lower overall sorption site density compared to previously studied thermophilic bacteria such Anoxybacillus flavithermus, Geobacillus stearothermophilus, G. thermocatenulatus, and Thermus thermophilus. The thermophilic bacteria and archaea display lower sorption site densities than the mesophilic microorganisms that have been studied to date, which points to a general pattern of total concentration of cell wall adsorption sites per unit biomass being inversely correlated to growth temperature

Multilaboratory Evaluation of Real-Time PCR Tests for Hepatitis B Virus DNA Quantification

The performance characteristics of four different assays for hepatitis B virus (HBV) quantification were assessed: the Abbott RealTime HBV IUO, the Roche Cobas AmpliPrep/Cobas TaqMan HBV test, the Roche Cobas TaqMan HBV test with HighPure system, and the Qiagen artus HBV TM ASR. Limit of detection (LOD), linear range, reproducibility, and agreement were determined using a serially diluted plasma sample from a single chronically infected subject. Each assay was tested by at least three laboratories. The LOD of the RealTime and two TaqMan assays was approximately 1.0 log10 IU/ml; for artus HBV (which used the lowest volume of extracted DNA), it was approximately 1.5 log10 IU/ml. The linear range spanned 1.0 to at least 7.0 log10 IU/ml for all assays. Median values were consistently lowest for artus HBV and highest for Cobas AmpliPrep/Cobas TaqMan HBV. Assays incorporating automated nucleic acid extraction were the most reproducible; however, the overall variability was minor since the standard deviations for the means of all tested concentrations were ≤0.32 log10 IU/ml for all assays. False-positive results were observed with all assays; the highest rates occurred with tests using manual nucleic acid extraction. The performance characteristics of these assays suggest that they are useful for management and therapeutic monitoring of chronic HBV infection

Galaxy And Mass Assembly (GAMA): the dependence of star formation on surface brightness in low-redshift galaxies

The star-formation rate in galaxies is well known to correlate with stellar mass (the ‘star-forming main sequence’). Here, we extend this further to explore any additional dependence on galaxy surface brightness, a proxy for stellar mass surface density. We use a large sample of low-redshift (z ≤ 0.08) galaxies from the Galaxy And Mass Assembly survey which have both spectral energy distribution (SED) derived star-formation rates and photometric bulge-disc decompositions, the latter providing measures of disc surface brightness and disc masses. Using two samples, one of galaxies fitted by a single component with Sérsic index below 2 and one of the discs from two-component fits, we find that once the overall mass dependence of star-formation rate is accounted for, there is no evidence in either sample for a further dependence on stellar surface density

Dynamics of M-Theory Cosmology

A complete global analysis of spatially-flat, four-dimensional cosmologies derived from the type IIA string and M-theory effective actions is presented. A non--trivial Ramond-Ramond sector is included. The governing equations are written as a dynamical system. Asymptotically, the form fields are dynamically negligible, but play a crucial role in determining the possible intermediate behaviour of the solutions (i.e. the nature of the equilibrium points). The only past-attracting solution (source in the system) may be interpreted in the eleven-dimensional setting in terms of flat space. This source is unstable to the introduction of spatial curvature.Comment: 13 pages, 4 Postscript figures, uses graphics.sty, submitted to Phys. Rev.

Galaxy And Mass Assembly (GAMA): Defining Passive Galaxy Samples and Searching for the UV Upturn

Abstract We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes internal to individual galaxies with no measurable influence from the galaxies’ larger environment. We first define a clean sample of passive galaxies without a significant contribution to their UV flux from low-level star formation. We confirm that galaxies with the optical colours of red sequence galaxies often have signs of residual star formation, which, without other information, would prevent a convincing demonstration of the presence of UV upturns. However, by including (NUV−u) and WISE (W2-W3) colours, and FUV data where it exists, we can convincingly constrain samples to be composed of non-star-forming objects. Using such a sample, we examine GALEX photometry of low redshift GAMA galaxies in a range of low-density environments, from groups to the general field, searching for UV upturns. We find a wide range of (NUV−r) colours, entirely consistent with the range seen – and attributed to the UV upturn – in low-redshift red sequence cluster galaxies. The range of colours is independent of group multiplicity or velocity dispersion, with isolated passive galaxies just as likely to have blue UV-to-optical colours, implying significant upturn components, as those in richer groups and in the previous data on clusters. This is supported by equivalent results for (FUV−r) colours which are clear indicators of upturn components

Observational constraints on the physical nature of submillimetre source multiplicity : chance projections are common

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Interferometric observations have demonstrated that a significant fraction of single-dish submillimetre (submm) sources are blends of multiple submm galaxies (SMGs), but the nature of this multiplicity, i.e. whether the galaxies are physically associated or chance projections, has not been determined.We performed spectroscopy of 11 SMGs in six multicomponent submm sources, obtaining spectroscopic redshifts for nine of them. For an additional two component SMGs, we detected continuum emission but no obvious features.We supplement our observed sources with four single-dish submm sources from the literature. This sample allows us to statistically constrain the physical nature of single-dish submm source multiplicity for the first time. In three (3/7, or 43 -33 +39 per cent at 95 per cent confidence) of the single-dish sources for which the nature of the blending is unambiguous, the components for which spectroscopic redshifts are available are physically associated, whereas 4/7 (57 -39 +33 per cent) have at least one unassociated component. When components whose spectra exhibit continuum but no features and for which the photometric redshift is significantly different from the spectroscopic redshift of the other component are also considered, 6/9 (67 -37 +26 per cent) of the single-dish sources are comprised of at least one unassociated component SMG. The nature of the multiplicity of one single-dish source is ambiguous. We conclude that physically associated systems and chance projections both contribute to the multicomponent single-dish submm source population. This result contradicts the conventional wisdom that bright submm sources are solely a result of merger-induced starbursts, as blending of unassociated galaxies is also important.Peer reviewe

A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam

A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.Comment: 209 pages, 129 figure

Galaxy and Mass Assembly (GAMA): Variation in galaxy structure across the green valley

Using a sample of 472 local Universe (z \u3c 0.06) galaxies in the stellar mass range 10.25 \u3c logM*/M⊙ \u3c 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is subdivided into red, green, and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies. Using Kilo- Degree Survey (KiDS) and Visible and Infrared Survey Telescope for Astronomy (VISTA) Kilo-Degree Infrared Galaxy Survey (VIKING) derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells, and signs of merger activity for all systems. We find a significant surplus of rings (2.3s) and lenses (2.9s) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3s relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ~44 per cent which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ~20-30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0s surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley

Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described