A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143

We report on the analysis of a ∼60-ks XMM–Newton observation of the bright, narrow emission line quasar PG1211+143. Absorption lines are seen in both European Photon Imaging Camera and Reflection Grating Spectrometer spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C. The observed line energies indicate an ionized outflow velocity of ∼24 000 km s⁻¹. The highest energy lines require a column density of   N _H∼ 5 × 10²³ cm⁻²  , at an ionization parameter of  log ξ∼ 3.4  . If the origin of this high-velocity outflow lies in matter being driven from the inner disc, then the flow is likely to be optically thick within a radius of ∼130 Schwarzschild radii, providing a natural explanation for the big blue bump (and strong soft X-ray) emission in PG1211+143.     

Variability in the power spectrum of solar five-minute oscillations

Two-dimensional power spectra of solar five-minute oscillations display prominent ridge structures in (k, ω) space, where k is the horizontal wavenumber and ω is the temporal frequency. The positions of these ridges in k and ω can be used to probe temperature and velocity structures in the subphotosphere. We have been carrying out a continuing program of observations of five-minute oscillations with the diode array instrument on the vacuum tower telescope at Sacramento Peak Observatory (SPO). We have sought to establish whether power spectra taken on separate days show shifts in ridge locations; these may arise from different velocity and temperature patterns having been brought into our sampling region by solar rotation. Power spectra have been obtained for six days of observations of Doppler velocities using the Mgi λ5173 and Fei λ5434 spectral lines. Each data set covers 8 to 11 hr in time and samples a region 256″ × 1024″ in spatial extent, with a spatial resolution of 2″ and temporal sampling of 65 s. We have detected shifts in ridge locations between certain data sets which are statistically significant. The character of these displacements when analyzed in terms of eastward and westward propagating waves implies that changes have occurred in both temperature and horizontal velocity fields underlying our observing window. We estimate the magnitude of the velocity changes to be on the order of 100 m s^-1; we may be detecting the effects of large-scale convection akin to giant cells.     

The Finnmarkian Orogeny revisited: An isotopic investigation in eastern Finnmark, Arctic Norway

The Scandinavian Caledonides have been viewed as resulting from either a single Silurian (i.e. Scandian) event or from polycyclic orogenies involving several collisions on the margin of Baltica. Early studies of the Kalak Nappe Complex (KNC) in Finnmark, Arctic Norway, led to the hypothesis of an Early Cambrian-Early Ordovician (520-480 Ma) Finnmarkian Orogeny, though the nature of this tectonic event remains enigmatic. In this contribution we have employed in situ UV laser ablation Ar-Ar dating of fine-grained phyllite and schist from the eastern Caledonides of Arctic Norway to investigate the presence of pre-Scandian tectonometamorphic events. U-Th-Pb detrital zircon and whole rock Sm-Nd analyses have been used to test the regional stratigraphic correlations of these metasedimentary rocks. These results indicate that the Berlevåg Formation within the Tanafjord Nappe, previously assumed to be part of the KNC, was deposited after 1872 Ma and prior to a low temperature hydrothermal event at 555 ± 15 Ma. It has a likely provenance on the Baltica continent, lacks any Grenville-Sveconorwegian detrital zircons, and thus cannot be part of the KNC which contains abundant detritus in this age range. Instead the Berlevåg Formation is interpreted as part of the Laksefjord Nappe Complex, which structurally underlies the KNC. Laser-ablation argon-argon dating also shows that late Caledonian (i.e. Scandian) tectonometamorphism affected both the KNC and its immediate footwall at c. 425 ± 15 Ma. This is corroborated by a step-heating argon-argon muscovite age of 424 ± 3 Ma which is interpreted as dating cooling. However, within two samples from the KNC, an earlier (Middle-Late Cambrian) metamorphic event is also recorded. A biotite-grade schist yielded an Ar-Ar inverse isochron age of 506 ± 17 Ma from whole rock surfaces, in which the mineral domains are too fine-grained to date individually. An early generation of muscovite from a coarser-grained amphibolite-facies sample yielded an inverse isochron of 498 ± 13 Ma. Both isochron ages have atmospheric argon intercept values. Previous studies have documented similar Cambrian ages in the Caledonian nappes below the KNC. These results suggest correlative tectonometamorphic events in the eastern KNC and its footwall at c. 500 Ma. This Cambrian event may reflect the arrival of the Kalak Nappe Complex as a previously constructed exotic mobile belt onto the margin of Baltica. Combined with recent studies from the western Kalak Nappe Complex, the results do not support the traditional constraint on the Finnmarkian Orogeny sensu stricto. However they vindicate classic tectonic models involving a Cambrian accretion event.     

The effect of extracellular polymers (EPS) on the proton adsorption characteristics of the thermophile Bacillus licheniformis S-86

This study investigated proton adsorption to an extracellular polymeric substance (EPS) producing bacterial strain, Bacillus licheniformis S-86, in order to characterise and quantify the contribution made by EPS to cell surface reactivity. Potentiometric titrations were conducted using both untreated cells and cells from which the EPS layer had been extracted. Surface-complexation modelling indicated the presence of four different functional groups in both untreated and EPS-free cells. These sites are assigned to phosphodiester, (pK_a 3.3–3.4), carboxylic (pK_a 5.3–5.4), phosphoryl/ (pK_a 7.4–7.5) and hydroxyl/amine (pK_a 9.9–10.1) type groups. The pK_a values for the four groups were very similar for untreated and EPS-free cells, indicating no qualitative difference in composition, but site concentrations in the untreated cells were statistically found to be significantly higher than those in the EPS-free cells for the pK_a 3.3–3.4 and pK_a 9.9–10.1 sites. Infrared analysis provided supporting evidence that site 2 is carboxylic in nature but did not reveal any difference in IR absorption between the native and EPS-free cells. Dissolved organic carbon (DOC) analysis conducted during this study indicated that DOC release by cells is significant, and that the EPS layer is the major contributor.     

Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

Voracious planktonic hydroids: unexpected predatory impact on a coastal marine ecosystem

Hydroids are typically attached, benthic cnidarians that feed on a variety of small prey. During sampling on Georges Bank in spring 1994, we found huge numbers of hydroids suspended in the plankton. They fed on young stages of copepods that are an important prey for fish, as well as on young fish themselves. Two independent methods were used to estimate feeding rates of the hydroids; both indicate that the hydroids are capable of consuming from 50% to over 100% of the daily production of young copepods. These results suggest that hydroids can have a profound effect on the population dynamics of zooplankton and young fish on Georges Bank.     

Effects of organic toxicants on the anoxic energy metabolism of the mussel Mytilus edulis

The anoxic rates of heat dissipation by mussels (Mytilus edulis) were enhanced after exposure to pentachlorophenol (PCP) and tributyltin (TBT), both known uncouplers of oxidative phosphorylation. The degree of metabolic activation under anoxia was dependent upon the amount of toxicant accumulated in the tissues, but the concentration-response relationship was different to that under aerobic conditions. Biochemical measurements indicated that the anaerobic metabolic pathways were significantly disturbed by PCP and TBT. There was a decline in succinate, an increase in the fumarate: succinate ratio, and an increase in the accumulation of lactate, indicating a shift from succinate to lactate anaerobic pathways. A consequence of organic toxicant exposure was a reduction in anoxic survival time of mussels.