Do galaxies that leak ionizing photons have extreme outflows?

To reionize the early universe, high-energy photons must escape the galaxies that produce them. It has been suggested that stellar feedback drives galactic outflows out of star-forming regions, creating low density channels through which ionizing photons escape into the inter-galactic medium. We compare the galactic outflow properties of confirmed Lyman continuum (LyC) leaking galaxies to a control sample of nearby star-forming galaxies to explore whether the outflows from leakers are extreme as compared to the control sample. We use data from the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure the equivalent widths and velocities of Si II and Si III absorption lines, tracing neutral and ionized galactic outflows. We find that the Si II and Si III equivalent widths of the LyC leakers reside on the low-end of the trend established by the control sample. The leakers' velocities are not statistically different than the control sample, but their absorption line profiles have a different asymmetry: their central velocities are closer to their maximum velocities. The outflow kinematics and equivalent widths are consistent with the scaling relations between outflow properties and host galaxy properties -- most notably metallicity -- defined by the control sample. Additionally, we use the Ly\alpha\ profiles to show that the Si II equivalent width scales with the Ly\alpha\ peak velocity separation. We determine that the low equivalent widths of the leakers are likely driven by low metallicities and low H I column densities, consistent with a density-bounded ionization region, although we cannot rule out significant variations in covering fraction. While we do not find that the LyC leakers have extreme outflow velocities, the low maximum-to-central velocity ratios demonstrate the importance of the acceleration and density profiles for LyC and Ly\alpha\ escape. [abridged]Comment: 17 pages, 8 Figures. Accepted for publication in Astronomy & Astrophysic

Preliminary flight evaluation of an engine performance optimization algorithm

A performance seeking control (PSC) algorithm has undergone initial flight test evaluation in subsonic operation of a PW 1128 engined F-15. This algorithm is designed to optimize the quasi-steady performance of an engine for three primary modes: (1) minimum fuel consumption; (2) minimum fan turbine inlet temperature (FTIT); and (3) maximum thrust. The flight test results have verified a thrust specific fuel consumption reduction of 1 pct., up to 100 R decreases in FTIT, and increases of as much as 12 pct. in maximum thrust. PSC technology promises to be of value in next generation tactical and transport aircraft

Intense CIII] 1907,1909 emission from a strong Lyman continuum emitting galaxy

We have obtained the first complete ultraviolet (UV) spectrum of a strong Lyman continuum(LyC) emitter at low redshift -- the compact, low-metallicity, star-forming galaxy J1154+2443 -- with a Lyman continuum escape fraction of 46% discovered recently. The Space Telescope Imaging Spectrograph spectrum shows strong Lya and CIII] 1909 emission, as well as OIII] 1666. Our observations show that strong LyC emitters can have UV emission lines with a high equivalent width (e.g. EW(CIII])$=11.7 \pm 2.9 \AA$ rest-frame), although their equivalent widths should be reduced due to the loss of ionizing photons. The intrinsic ionizing photon production efficiency of J1154+2443 is high, $\log(\xi_{\rm ion}^0)=25.56$ erg$^{-1}$ Hz, comparable to that of other recently discovered $z \sim 0.3-0.4$ LyC emitters. Combining our measurements and earlier determinations from the literature, we find a trend of increasing $\xi_{\rm ion}^0$ with increasing CIII] 1909 equivalent width, which can be understood by a combination of decreasing stellar population age and metallicity. Simple ionization and density-bounded photoionization models can explain the main observational features including the UV spectrum of J1154+2443.Comment: 5 pages, 4 figures. Accepted for publication in A&A Letter

Assessment of novel binocular colour, motion and contrast tests in glaucoma

The effects of glaucoma on binocular visual sensitivity for the detection of various stimulus attributes are investigated at the fovea and in four paracentral retinal regions. The study employed a number of visual stimuli designed to isolate the processing of various stimulus attributes. We measured absolute contrast detection thresholds and functional contrast sensitivity by using Landolt ring stimuli. This psychophysical Landolt C-based contrast test of detection and gap discrimination allowed us to test parafoveally at 6 ° from fixation and foveally by employing interleaved testing locations. First-order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which utilises random dynamic luminance contrast noise (± 45 %) to ensure that only colour and not luminance signals are available for target detection. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyzer mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. Progression of loss was noted for all tests as the degree of glaucoma increased. For subjects with mild glaucoma (MD −0.01 dB to −6.00 dB) significantly more data points fell outside the normal age-representative range for RG colour thresholds than for any other visual test, followed by motion thresholds. This was particularly the case for the parafoveal data compared with the foveal data. Thus, a multifaceted measure of binocular visual performance, incorporating RG colour and motion test at multiple locations, might provide a better index for comparison with quality of life measures in glaucoma

Imperfect identity

Questions of identity over time are often hard to answer. A long tradition has it that such questions are somehow soft: they have no unique, determinate answer, and disagreements about them are merely verbal. I argue that this claim is not the truism it is taken to be. Depending on how it is understood, it turns out either to be false or to presuppose a highly contentious metaphysical claim

Expanded genetic screening in Caenorhabditis elegans identifies new regulators and an inhibitory role for NAD+ in axon regeneration.

The mechanisms underlying axon regeneration in mature neurons are relevant to the understanding of normal nervous system maintenance and for developing therapeutic strategies for injury. Here, we report novel pathways in axon regeneration, identified by extending our previous function-based screen using the C. elegans mechanosensory neuron axotomy model. We identify an unexpected role of the nicotinamide adenine dinucleotide (NAD+) synthesizing enzyme, NMAT-2/NMNAT, in axon regeneration. NMAT-2 inhibits axon regrowth via cell-autonomous and non-autonomous mechanisms. NMAT-2 enzymatic activity is required to repress regrowth. Further, we find differential requirements for proteins in membrane contact site, components and regulators of the extracellular matrix, membrane trafficking, microtubule and actin cytoskeleton, the conserved Kelch-domain protein IVNS-1, and the orphan transporter MFSD-6 in axon regrowth. Identification of these new pathways expands our understanding of the molecular basis of axonal injury response and regeneration

Exploring Eye Movements in Patients with Glaucoma When Viewing a Driving Scene

Background: Glaucoma is a progressive eye disease and a leading cause of visual disability. Automated assessment of the visual field determines the different stages in the disease process: it would be desirable to link these measurements taken in the clinic with patient's actual function, or establish if patients compensate for their restricted field of view when performing everyday tasks. Hence, this study investigated eye movements in glaucomatous patients when viewing driving scenes in a hazard perception test (HPT). Methodology/Principal Findings: The HPT is a component of the UK driving licence test consisting of a series of short film clips of various traffic scenes viewed from the driver's perspective each containing hazardous situations that require the camera car to change direction or slow down. Data from nine glaucomatous patients with binocular visual field defects and ten age-matched control subjects were considered (all experienced drivers). Each subject viewed 26 different films with eye movements simultaneously monitored by an eye tracker. Computer software was purpose written to pre-process the data, co-register it to the film clips and to quantify eye movements and point-of-regard (using a dynamic bivariate contour ellipse analysis). On average, and across all HPT films, patients exhibited different eye movement characteristics to controls making, for example, significantly more saccades (P<0.001; 95% confidence interval for mean increase: 9.2 to 22.4%). Whilst the average region of ‘point-of-regard’ of the patients did not differ significantly from the controls, there were revealing cases where patients failed to see a hazard in relation to their binocular visual field defect. Conclusions/Significance: Characteristics of eye movement patterns in patients with bilateral glaucoma can differ significantly from age-matched controls when viewing a traffic scene. Further studies of eye movements made by glaucomatous patients could provide useful information about the definition of the visual field component required for fitness to drive

The stability of a cubic fixed point in three dimensions from the renormalization group

The global structure of the renormalization-group flows of a model with isotropic and cubic interactions is studied using the massive field theory directly in three dimensions. The four-loop expansions of the \bt-functions are calculated for arbitrary $N$. The critical dimensionality $N_c=2.89 \pm 0.02$ and the stability matrix eigenvalues estimates obtained on the basis of the generalized Pad$\acute{\rm e}$-Borel-Leroy resummation technique are shown to be in a good agreement with those found recently by exploiting the five-loop \ve-expansions.Comment: 18 pages, LaTeX, 5 PostScript figure

The atomic structure of large-angle grain boundaries Σ5\Sigma 5 and Σ13\Sigma 13 in YBa2Cu3O7−δ{\rm YBa_2Cu_3O_{7-\delta}} and their transport properties

We present the results of a computer simulation of the atomic structures of large-angle symmetrical tilt grain boundaries (GBs) $\Sigma 5$ (misorientation angles \q{36.87}{^{\circ}} and \q{53.13}{^{\circ}}), $\Sigma 13$ (misorientation angles \q{22.62}{^{\circ}} and \q{67.38}{^{\circ}}). The critical strain level $\epsilon_{crit}$ criterion (phenomenological criterion) of Chisholm and Pennycook is applied to the computer simulation data to estimate the thickness of the nonsuperconducting layer ${\rm h_n}$ enveloping the grain boundaries. The ${\rm h_n}$ is estimated also by a bond-valence-sum analysis. We propose that the phenomenological criterion is caused by the change of the bond lengths and valence of atoms in the GB structure on the atomic level. The macro- and micro- approaches become consistent if the $\epsilon_{crit}$ is greater than in earlier papers. It is predicted that the symmetrical tilt GB $\Sigma5$ \theta = \q{53.13}{^{\circ}} should demonstrate a largest critical current across the boundary.Comment: 10 pages, 2 figure