Effect of Ocean Acidification on the Speciation of Metals in Seawater

Increasing atmospheric CO2 over the next 200 years will cause the pH of ocean waters to decrease further. Many recent studies have examined the effect of decreasing pH on calcifying organisms in ocean waters and on other biological processes (photosynthesis, nitrogen fixation, elemental ratios, and community structure). In this review, we examine how pH will change the organic and inorganic speciation of metals in surface ocean waters, and the effect that it will have on the interactions of metals with marine organisms. We consider both kinetic and equilibrium processes. The decrease in concentration of OH- and CO32- ions can affect the solubility, adsorption, toxicity, and rates of redox processes of metals in seawater. Future studies are needed to examine how pH affects the interactions of metals complexed to organic ligands and with marine organisms

Measuring Ejecta Velocity Improves Type Ia Supernova Distances

We use a sample of 121 spectroscopically normal Type Ia supernovae (SNe Ia) to show that their intrinsic color is correlated with their ejecta velocity, as measured from the blueshift of the Si II 6355 feature near maximum brightness, v_Si. The SN Ia sample was originally used by Wang et al. (2009) to show that the relationship between color excess and peak magnitude, which in the absence of intrinsic color differences describes a reddening law, was different for two subsamples split by v_Si (defined as "Normal" and "High-Velocity"). We verify this result, but find that the two subsamples have the same reddening law when extremely reddened events (E(B-V) > 0.35 mag) are excluded. We also show that (1) the High-Velocity subsample is offset by ~0.06 mag to the red from the Normal subsample in the (B_max - V_max) - M_V plane, (2) the B_max - V_max cumulative distribution functions of the two subsamples have nearly identical shapes, but the High-Velocity subsample is offset by ~0.07 mag to the red in B_max - V_max, and (3) the bluest High-Velocity SNe Ia are ~0.10 mag redder than the bluest Normal SNe Ia. Together, this evidence indicates a difference in intrinsic color for the subsamples. Accounting for this intrinsic color difference reduces the scatter in Hubble residuals from 0.190 mag to 0.130 mag for SNe Ia with A_V < 0.7 mag. The scatter can be further reduced to 0.109 mag by exclusively using SNe Ia from the Normal subsample. Additionally, this result can at least partially explain the anomalously low values of R_V found in large SN Ia samples. We explain the correlation between ejecta velocity and color as increased line blanketing in the High-Velocity SNe Ia, causing them to become redder. We discuss some implications of this result, and stress the importance of spectroscopy for future SN Ia cosmology surveys, with particular focus on the design of WFIRST.Comment: 9 pages, 8 figures, submitted to Ap

Diagnostic Utility of Major Basic Protein, Eotaxin-3 and Leukotriene Enzyme Staining in Eosinophilic Esophagitis

Features of eosinophilic esophagitis (EoE) and gastroesophageal reflux disease (GERD) overlap. We aimed to determine whether staining for tissue biomarkers would differentiate EoE from GERD, suggesting utility for diagnosis of EoE

Spectral Evolution of the Extraordinary Type IIn Supernova 2006gy

We present a detailed analysis of the extremely luminous Type IIn supernova SN2006gy using spectra obtained between days 36 and 237 after explosion. We derive the temporal evolution of the effective temperature, radius, expansion speeds, and bolometric luminosity, as well as the progenitor wind density and total swept-up mass overtaken by the shock. SN2006gy can be interpreted in the context of shock interaction with a dense CSM, but with quite extreme values for the CSM mass of 20 Msun and an explosion kinetic energy of at least 5e51 erg. A key difference between SN2006gy and other SNeIIn is that, owing to its large CSM mass, the interaction region remained opaque much longer. At early times, H-alpha widths suggest that the photosphere is ahead of the shock, and photons diffuse out through the opaque CSM. The pivotal transition to optically thin emission begins around day 110, when we start to see a decrease in the blackbody radius and strengthening tracers of the post-shock shell. From the evolution of pre-shock velocities, we deduce that the CSM was ejected by the progenitor in a 1e49 erg precursor event 8yr before explosion. The large CSM mass rules out models involving stars with initial masses around 10Msun. With the full mass budget, even massive M_ZAMS=30-40 Msun progenitor stars are inadequate. At roughly solar metallicity, substantial mass loss probably occurred during the star's life, so SN 2006gy's progenitor is more consistent with LBV eruptions or pulsational pair-instability ejections in stars with initial masses above 100 Msun. This requires significant revision to current paradigms of massive-star evolution. (abridged)Comment: Really long. 30 pages, 26 figs, appendix. Submitted to ApJ - v2 corrected one referenc

Tryptase Staining of Mast Cells May Differentiate Eosinophilic Esophagitis from Gastroesophageal Reflux Disease

Mast cells may contribute to the pathogenesis of eosinophilic esophagitis (EoE), but their role in diagnosis is unknown. Our aim was to determine whether tryptase staining of esophageal mast cells differentiates EoE from GERD and has utility for diagnosis of EoE

Sodium abundances in nearby disk stars

We present sodium abundances for a sample of nearby stars. All results have been derived from NLTE statistical equilibrium calculations. The influence of collisional interactions with electrons and hydrogen atoms is evaluated by comparison of the solar spectrum with very precise fits to the Na I line cores. The NLTE effects are more pronounced in metal-poor stars since the statistical equilibrium is dominated by collisions of which at least the electronic component is substantially reduced. The resulting influence on the determination of sodium abundances is in a direction opposite to that found previously for Mg and Al. The NLTE corrections are about -0.1 in thick-disk stars with [Fe/H] about -0.6. Our [Na/Fe] abundance ratios are about solar for thick- and thin-disk stars. The increase in [Na/Fe] as a function of [Fe/H] for metal-rich stars found by Edvardsson et al. (1993) is confirmed. Our results suggest that sodium yields increase with the metallicity, and quite large amounts of sodium may be produced by AGB stars. We find that [Na/Fe]ratios, together with either [Mg/Fe] ratio, kinematic data or stellar evolutionary ages, make possible the individual discrimination between thin- and thick-disk membership.Comment: 11pages, 11 figures. A&A accepte

The Low-Velocity, Rapidly Fading Type Ia Supernova 2002es

SN 2002es is a peculiar subluminous Type Ia supernova (SN Ia) with a combination of observed characteristics never before seen in a SN Ia. At maximum light, SN 2002es shares spectroscopic properties with the underluminous SN 1991bg subclass of SNe Ia, but with substantially lower expansion velocities (~6000 km/s) more typical of the SN 2002cx subclass. Photometrically, SN 2002es differs from both SN 1991bg-like and SN 2002cx-like supernovae. Although at maximum light it is subluminous (M_B=-17.78 mag), SN 2002es has a relatively broad light curve (Dm15(B)=1.28 +/- 0.04 mag), making it a significant outlier in the light-curve width vs. luminosity relationship. We estimate a 56Ni mass of 0.17 +/- 0.05 M_sun synthesized in the explosion, relatively low for a SN Ia. One month after maximum light, we find an unexpected plummet in the bolometric luminosity. The late-time decay of the light curves is inconsistent with our estimated 56Ni mass, indicating that either the light curve was not completely powered by 56Ni decay or the ejecta became optically thin to gamma-rays within a month after maximum light. The host galaxy is classified as an S0 galaxy with little to no star formation, indicating the progenitor of SN 2002es is likely from an old stellar population. We also present a less extensive dataset for SN 1999bh, an object which shares similar observed properties. Both objects were found as part of the Lick Observatory Supernova Search, allowing us to estimate that these objects should account for ~2.5% of SNe Ia within a fixed volume. We find that current theoretical models are unable to explain the observed of characteristics of SN 2002es.Comment: 19 pages, 15 figures, Submitted to Ap

The Concordance Cosmic Star Formation Rate: Implications from and for the Supernova Neutrino and Gamma Ray Backgrounds

We constrain the Cosmic Star Formation Rate (CSFR) by requiring that massive stars produce the observed UV, optical, and IR light while at the same time not overproduce the Diffuse Supernova Neutrino Background as bounded by Super-Kamiokande. With the massive star component so constrained we then show that a reasonable choice of stellar Initial Mass Function and other parameters results in SNIa rates and iron yields in good agreement with data. In this way we define a `concordance' CSFR that predicts the optical SNII rate and the SNIa contribution to the MeV Cosmic Gamma-Ray Background. The CSFR constrained to reproduce these and other proxies of intermediate and massive star formation is more clearly delineated than if it were measured by any one technique and has the following testable consequences: (1) SNIa contribute only a small fraction of the MeV Cosmic Gamma-Ray Background, (2) massive star core-collapse is nearly always accompanied by a successful optical SNII, and (3) the Diffuse Supernova Neutrino Background is tantalizingly close to detectability.Comment: Improved discussion. Version accepted for publication in JCA

Hypernovae and Other Black-Hole-Forming Supernovae

During the last few years, a number of exceptional core-collapse supernovae (SNe) have been discovered. Their kinetic energy of the explosions are larger by more than an order of magnitude than the typical values for this type of SNe, so that these SNe have been called `Hypernovae'. We first describe how the basic properties of hypernovae can be derived from observations and modeling. These hypernovae seem to come from rather massive stars, thus forming black holes. On the other hand, there are some examples of massive SNe with only a small kinetic energy. We suggest that stars with non-rotating black holes are likely to collapse "quietly" ejecting a small amount of heavy elements (Faint supernovae). In contrast, stars with rotating black holes are likely to give rise to very energetic supernovae (Hypernovae). We present distinct nucleosynthesis features of these two types of "black-hole-forming" supernovae. Hypernova nucleosynthesis is characterized by larger abundance ratios (Zn,Co,V,Ti)/Fe and smaller (Mn,Cr)/Fe. Nucleosynthesis in Faint supernovae is characterized by a large amount of fall-back. We show that the abundance pattern of the most Fe deficient star, HE0107-5240, and other extremely metal-poor carbon-rich stars are in good accord with those of black-hole-forming supernovae, but not pair-instability supernovae. This suggests that black-hole-forming supernovae made important contributions to the early Galactic (and cosmic) chemical evolution.Comment: 49 pages, to be published in "Stellar Collapse" (Astrophysics and Space Science; Kluwer) ed. C. L. Fryer (2003

Clinical and Endoscopic Characteristics do Not Reliably Differentiate PPI-Responsive Esophageal Eosinophilia and Eosinophilic Esophagitis in Patients Undergoing Upper Endoscopy: A Prospective Cohort Study

Proton pump inhibitor-responsive esophageal eosinophilia (PPI-REE) is a newly recognized entity that must be differentiated from eosinophilic esophagitis (EoE). Little is known about this condition. We aimed to determine the prevalence of PPI-REE and EoE in patients undergoing upper endoscopy, and determine features that distinguish the two groups