VLT Observations of Two Unusual BAL Quasars

Among the unusual broad absorption line quasars being found by the Sloan Digital Sky Survey (SDSS) are objects with much stronger absorption in Fe III than Fe II. These unusual line ratios require a high density in the outflow (n_H >= 3 x 10^{10} cm^{-3}). They should also appear for only a limited range of outflow column densities, which explains their rarity. Previously we suggested that the Fe III line ratios were also affected by a resonance; we now believe this is an artifact of structure in the underlying Fe II + Fe III pseudocontinuum. The SDSS is also discovering objects with absorption in rarely seen transitions such as He I. VLT+UVES high-resolution spectra of one such object, the mini-BAL quasar SDSS 1453+0029, show that it has two He I absorption systems with considerably different properties separated by only 350 km/s.Comment: 4 pages, 3 figures; to appear in "Active Galactic Nuclei, from Central Engine to Host Galaxy", eds. Collin, Combes & Shlosman, PASP Conference Series, in pres

An MHD-driven Disk Wind Outflow in SDSS J0300+0048?

The outflow in SDSS J030000.56+004828.0 has the highest low-ionization metal-line column density yet reported for a broad absorption line quasar. The absorption from different ions is also segregated as a function of velocity in a way that can only be explained by a disk wind outflow. Furthermore, the presence of the such large column densities of gas at the high observed outflow velocities may be incompatible with purely radiative acceleration. MHD contributions to the acceleration should be considered seriously.Comment: to appear in AGN Physics with the Sloan Digital Sky Survey, ed. G. T. Richards and P. B. Hal

A new look at an old view of denaturant induced protein unfolding

We re-examine a site-binding approach independently proposed by Schellman (Schellman, J.A. (1958) Compt. rend. Lab. Carlsberg Ser. Chim. 30, 439-449) and Aune and Tanford (Aune, K.C. and Tanford, D. (1969) Biochemistry, 8, 4586-4590) for explicitly including the denaturant concentration within the protein unfolding equilibrium. We extend and formalize the approach through development of a multi-dimensional analytical model in which the folding reaction coordinate is defined by the number of denaturant molecules bound to sites located on either the initially folded, or unfolded, states of the protein. We use the developed method to re-examine the mechanistic determinants underlying the sigmoidal shape of the unfolding transition. A natural feature of our method is that it presents a landscape picture of the denaturant induced protein unfolding reaction

Visual information search in simulated junction negotiation: Gaze transitions of young novice, young experienced and older experienced drivers.

Older drivers and young novice drivers have problems negotiating road junctions and this is reflected in the accident statistics for these driver populations. Explanations for problems with junction negotiation largely focus on limitations in visual information processing and observation errors associated with age and experience. Investigations of drivers viewing behaviour have used measures of fixation and gaze frequency and duration to highlight drivers information processing and search, capacity and requirements. The use of more specific measures of search strategy, such as gaze transitions, has been less common, particularly for the task of gap selection in junction negotiation. Gaze transitions provide information on the positional relationship of fixations, providing a useful tool for highlighting gaps in driver’s visual information acquisition strategies. The gaze transitions of three driver groups (young novice, young experienced and older experienced) were compared during gap selection in right turn junction negotiation manoeuvres. When scanning the junction, young experienced drivers distributed their gaze more evenly across all areas, whereas older and novice drivers made more sweeping transitions, bypassing adjacent areas. The use of a preview strategy in the decision phase was less evident in the older experienced group compared to the younger groups. It is suggested that response preparation requirements of the decision phase impact on older drivers’ ability to maintain a preview strategy. The application of results to driver training interventions and future research are discussed

Acceleration and Substructure Constraints in a Quasar Outflow

We present observations of probable line-of-sight acceleration of a broad absorption trough of C IV in the quasar SDSS J024221.87+004912.6. We also discuss how the velocity overlap of two other outflowing systems in the same object constrains the properties of the outflows. The Si IV doublet in each system has one unblended transition and one transition which overlaps with absorption from the other system. The residual flux in the overlapping trough is well fit by the product of the residual fluxes in the unblended troughs. For these optically thick systems to yield such a result, at least one of them must consist of individual subunits rather than being a single structure with velocity-dependent coverage of the source. If these subunits are identical, opaque, spherical clouds, we estimate the cloud radius to be r = 3.9 10^15 cm. If they are identical, opaque, linear filaments, we estimate their width to be w = 6.5 10^14 cm. These subunits are observed to cover the Mg II broad emission line region of the quasar, at which distance from the black hole the above filament width is equal to the predicted scale height of the outer atmosphere of a thin accretion disk. Insofar as that scale height is a natural size scale for structures originating in an accretion disk, these observations are evidence that the accretion disk can be a source of quasar absorption systems. Based on data from ESO program 075.B-0190(A).Comment: 14 emulateapj pages, 7 figures, ApJ in pres

A structural and functional study of Gln147 deamidation in aA-crystallin, a site of modification in human cataract

Deamidation of Glu147 in human αA-crystallin is common in aged cataractous lenses (Hains and Truscott, Invest. Ophthalmol. Vis. Sci. 2010, 51, 3107). Accordingly, this modification may have a causative effect in cataract. αA-crystallin is a small heat-shock molecular chaperone protein that prevents aggregation of proteins and is the principal defence against crystallin unfolding and aggregation in the ageing lens. Deamidated Q147E αA-crystallin was structurally characterised using a variety of spectroscopic and biophysical methods, including NMR, circular dichroism and fluorescence spectroscopy and dynamic light scattering. The effect of Glu147 deamidation on αA-crystallin in vitro chaperone ability was determined for a variety of aggregating proteins. Compared to the wild type protein, Q147E αA-crystallin generally exhibited slightly reduced chaperone ability and a small loss of overall structure in its central α-crystallin domain while also showing significantly enhanced thermal stability and a tendency to form slightly larger oligomers. As αA-crystallin is the major lens protein, even a small loss of function could combine with other sources of age-related damage to the crystallins to contribute to lens opacification.This work was supported by a grant (#1068087) to JC from the National Health and Medical Research Council of Australia

Synthetic Access to Ring-Expanded N-Heterocyclic Carbene (RE-NHC) Copper Complexes and their Performance in Click Chemistry

The facile syntheses of ring-expanded N-heterocyclic carbene (RE-NHC) copper(I) halide complexes are reported. The method makes use of a weak inorganic base in a green solvent. The reaction times can be greatly reduced by use of this weak-base route under microwave irradiation. The easy access to these complexes permits an evaluation of the catalytic activity and reaction profiling of [Cu(RE-NHC)X] complexes in the Huisgen 1,3-cycloaddition reaction