2,894 research outputs found

    Review: The Newsletter of the Literary Managers and Dramaturgs of the Americas, volume 13, issue 2

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    Contents include: On Borders, LMDA Conference 2003 Turgs in the Hood, Reading Between the Lines, Acting Locally: The Lysistrata Project, and Regional Updates News and Info from Each LMDA Region. Issue editors: D.J. Hopkins, Shelley Orr, Liz Engelman, Madeline Oldham, Jacob Zimmer.https://soundideas.pugetsound.edu/lmdareview/1027/thumbnail.jp

    Large scale outflows from z ~ 0.7 starburst galaxies identified via ultra-strong MgII quasar absorption lines

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    (Abridged) Star formation-driven outflows are a critical phenomenon in theoretical treatments of galaxy evolution, despite the limited ability of observations to trace them across cosmological timescales. If the strongest MgII absorption-line systems detected in the spectra of background quasars arise in such outflows, "ultra-strong" MgII (USMgII) absorbers would identify significant numbers of galactic winds over a huge baseline in cosmic time, in a manner independent of the luminous properties of the galaxy. To this end, we present the first detailed imaging and spectroscopic study of the fields of two USMgII absorber systems culled from a statistical absorber catalog, with the goal of understanding the physical processes leading to the large velocity spreads that define such systems. Each field contains two bright emission-line galaxies at similar redshift (dv < 300 km/s) to that of the absorption. Lower-limits on their instantaneous star formation rates (SFR) from the observed OII and Hb line fluxes, and stellar masses from spectral template fitting indicate specific SFRs among the highest for their masses at z~0.7. Additionally, their 4000A break and Balmer absorption strengths imply they have undergone recent (~0.01 - 1 Gyr) starbursts. The concomitant presence of two rare phenomena - starbursts and USMgII absorbers - strongly implies a causal connection. We consider these data and USMgII absorbers in general in the context of various popular models, and conclude that galactic outflows are generally necessary to account for the velocity extent of the absorption. We favour starburst driven outflows over tidally-stripped gas from a major interaction which triggered the starburst as the energy source for the majority of systems. Finally, we discuss the implications of these results and speculate on the overall contribution of such systems to the global SFR density at z~0.7.Comment: 15 pages, 6 figure, accepted for publication by MNRA

    Regulation of PTEN Inhibition by the Pleckstrin Homology Domain of P-REX2 During Insulin Signaling and Glucose Homeostasis

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    Insulin activation of phosphoinositide 3-kinase (PI3K) signaling regulates glucose homeostasis through the production of phosphatidylinositol 3,4,5-trisphosphate (PIP3). The dual-specificity phosphatase and tensin homolog deleted on chromosome 10 (PTEN) blocks PI3K signaling by dephosphorylating PIP3, and is inhibited through its interaction with phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 2 (P-REX2). The mechanism of inhibition and its physiological significance are not known. Here, we report that P-REX2 interacts with PTEN via two interfaces. The pleckstrin homology (PH) domain of P-REX2 inhibits PTEN by interacting with the catalytic region of PTEN, and the inositol polyphosphate 4-phosphatase domain of P-REX2 provides high-affinity binding to the postsynaptic density-95/Discs large/zona occludens-1-binding domain of PTEN. P-REX2 inhibition of PTEN requires C-terminal phosphorylation of PTEN to release the P-REX2 PH domain from its neighboring diffuse B-cell lymphoma homology domain. Consistent with its function as a PTEN inhibitor, deletion of Prex2 in fibroblasts and mice results in increased Pten activity and decreased insulin signaling in liver and adipose tissue. Prex2 deletion also leads to reduced glucose uptake and insulin resistance. In human adipose tissue, P-REX2 protein expression is decreased and PTEN activity is increased in insulin-resistant human subjects. Taken together, these results indicate a functional role for P-REX2 PH-domain-mediated inhibition of PTEN in regulating insulin sensitivity and glucose homeostasis and suggest that loss of P-REX2 expression may cause insulin resistance

    The robustness of cosmological hydrodynamic simulation predictions to changes in numerics and cooling physics

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    We test and improve the numerical schemes in our smoothed particle hydrodynamics (SPH) code for cosmological simulations, including the pressure-entropy formulation (PESPH), a time-dependent artificial viscosity, a refined timestep criterion, and metal-line cooling that accounts for photoionisation in the presence of a recently refined Haardt \& Madau (2012) model of the ionising background. The PESPH algorithm effectively removes the artificial surface tension present in the traditional SPH formulation, and in our test simulations it produces better qualitative agreement with mesh-code results for Kelvin-Helmholtz instability and cold cloud disruption. Using a set of cosmological simulations, we examine many of the quantities we have studied in previous work. Results for galaxy stellar and HI mass functions, star formation histories, galaxy scaling relations, and statistics of the Lyα\alpha forest are robust to the changes in numerics and microphysics. As in our previous simulations, cold gas accretion dominates the growth of high-redshift galaxies and of low mass galaxies at low redshift, and recycling of winds dominates the growth of massive galaxies at low redshift. However, the PESPH simulation removes spurious cold clumps seen in our earlier simulations, and the accretion rate of hot gas increases by up to an order of magnitude at some redshifts. The new numerical model also influences the distribution of metals among gas phases, leading to considerable differences in the statistics of some metal absorption lines, most notably NeVIII.Comment: 29 pages, 25 figures, accepted by MNRA

    A Simple Likelihood Method for Quasar Target Selection

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    We present a new method for quasar target selection using photometric fluxes and a Bayesian probabilistic approach. For our purposes we target quasars using Sloan Digital Sky Survey (SDSS) photometry to a magnitude limit of g=22. The efficiency and completeness of this technique is measured using the Baryon Oscillation Spectroscopic Survey (BOSS) data, taken in 2010. This technique was used for the uniformly selected (CORE) sample of targets in BOSS year one spectroscopy to be realized in the 9th SDSS data release. When targeting at a density of 40 objects per sq-deg (the BOSS quasar targeting density) the efficiency of this technique in recovering z>2.2 quasars is 40%. The completeness compared to all quasars identified in BOSS data is 65%. This paper also describes possible extensions and improvements for this techniqueComment: Updated to accepted version for publication in the Astrophysical Journal. 10 pages, 10 figures, 3 table
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