Zooming in on accretion - II. Cold Circumgalactic Gas Simulated with a super-Lagrangian Refinement Scheme

In this study we explore the complex multi-phase gas of the circumgalactic medium (CGM) surrounding galaxies. We propose and implement a novel, super-Lagrangian 'CGM zoom' scheme in the moving-mesh code AREPO, which focuses more resolution into the CGM and intentionally lowers resolution in the dense ISM. We run two cosmological simulations of the same galaxy halo, once with a simple 'no feedback' model, and separately with a more comprehensive physical model including galactic-scale outflows as in the Illustris simulation. Our chosen halo has a total mass of ~10^12 Msun at z ~ 2, and we achieve a median gas mass (spatial) resolution of ~2,200 solar masses (~95 parsecs) in the CGM, six-hundred (fourteen) times better than in the Illustris-1 simulation, a higher spatial resolution than any cosmological simulation at this mass scale to date. We explore the primary channel(s) of cold-phase CGM gas production in this regime. We find that winds substantially enhance the amount of cold gas in the halo, also evidenced in the covering fractions of HI and the equivalent widths of MgII out to large radii, in better agreement with observations than the case without galactic winds. Using a tracer particle analysis to follow the thermodynamic history of gas, we demonstrate how the majority of this cold, dense gas arises due to rapid cooling of the wind material interacting with the hot halo, and how large amounts of cold, ~10^4 K gas can be produced and persist in galactic halos with Tvir ~ 10^6 K. At the resolutions presently considered, the quantitative properties of the CGM we explore are not appreciably affected by the refinement scheme.Comment: MNRAS submitted, comments welcome. High-res version at http://www.mpa-garching.mpg.de/~dnelson/papers/Suresh19_zooming2.pd

The Declining Value Relevance of Accounting Information and Non Information-Based Trading: An Empirical Analysis

Recently, a growing body of literature has suggested that financial statements have lost their value relevance because of a shift from a traditional capital-intensive economy to a hightechnology, service-oriented economy. These conclusions are based on studies that find a temporal decline in the association between stock prices and accounting information (earnings and book values). This paper empirically tests a theoretical prediction arising from the Noisy Rational Expectations Equilibrium model that suggests that the decline could be driven by noninformation- based (NIB) trading activity, because such trading reduces the ability of stock prices to reflect accounting information. Specifically, Dontoh et al. (2004) show that when NIB trading increases, the R-squares of a regression of stock price on accounting information declines. Our empirical tests confirm this prediction; i.e., the decline in the association between stock prices and accounting information as measured by R-squares is driven by an increase in NIB trading

On the Cosmic Evolution of Fe/Mg in QSO Absorption Line Systems

We investigate the variation of the ratio of the equivalent widths of the FeII$\lambda$2600 line to the MgII$\lambda\lambda$2796,2803 doublet as a function of redshift in a large sample of absorption lines drawn from the JHU-SDSS Absorption Line Catalog. We find that despite large scatter, the observed ratio shows a trend where the equivalent width ratio $\mathcal{R}\equiv W_{\rm FeII}/W_{\rm MgII}$ decreases monotonically with increasing redshift $z$ over the range $0.55 \le z \le 1.90$. Selecting the subset of absorbers where the signal-to-noise ratio of the MgII equivalent width $W_{\rm MgII}$ is $\ge$3 and modeling the equivalent width ratio distribution as a gaussian, we find that the mean of the gaussian distribution varies as $\mathcal{R}\propto (-0.045\pm0.005)z$. We discuss various possible reasons for the trend. A monotonic trend in the Fe/Mg abundance ratio is predicted by a simple model where the abundances of Mg and Fe in the absorbing clouds are assumed to be the result of supernova ejecta and where the cosmic evolution in the SNIa and core-collapse supernova rates is related to the cosmic star-formation rate. If the trend in $\mathcal{R}$ reflects the evolution in the abundances, then it is consistent with the predictions of the simple model.Comment: 10 pages, 4 figures, final version published in MNRA

The Incremental Information Content of Tone Change in Management Discussion and Analysis

This study explores whether the Management Discussion and Analysis (MD&A) section of Form 10-Q and 10-K has incremental information content beyond financial measures such as earnings surprises, accruals and operating cash flows (OCF). It uses a well-established classification scheme of words into positive and negative categories to measure the tone change in a specific MD&A section as compared to those of the prior four filings. Our results indicate that short window market reactions around the SEC filing are significantly associated with the tone of the MD&A section, even after controlling for accruals, OCF and earnings surprises. We also show that the tone of the MD&A section adds significantly to portfolio drift returns in the window of two days after the SEC filing date through one day after the subsequent quarter’s preliminary earnings announcement, beyond financial information conveyed by accruals, OCF and earnings surprises. The incremental information of tone change is larger the weaker is the firm’s information environment

Synergism in hyperhomocysteinemia and diabetes: role of PPAR gamma and tempol

<p>Abstract</p> <p>Background</p> <p>Hyperhomocysteinemia (HHcy) and hyperglycemia cause diabetic cardiomyopathy by inducing oxidative stress and attenuating peroxisome proliferator- activated receptor (PPAR) gamma. However, their synergistic contribution is not clear.</p> <p>Methods</p> <p>Diabetic Akita (Ins2+/-) and hyperhomocysteinemic cystathionine beta synthase mutant (CBS+/-) were used for M-mode echocardiography at the age of four and twenty four weeks. The cardiac rings from WT, Akita and hybrid (Ins2+/-/CBS+/-) of Akita and CBS+/- were treated with different doses of acetylcholine (an endothelial dependent vasodilator). High performance liquid chromatography (HPLC) was performed for determining plasma homocysteine (Hcy) level in the above groups. Akita was treated with ciglitazone (CZ) - a PPAR gamma agonist and tempol-an anti-oxidant, separately and their effects on cardiac remodeling were assessed.</p> <p>Results</p> <p>At twenty four week, Akita mice were hyperglycemic and HHcy. They have increased end diastolic diameter (EDD). In their heart PPAR gamma, tissue inhibitor of metalloproteinase-4 (TIMP-4) and anti-oxidant thioredoxin were attenuated whereas matrix metalloproteinase (MMP)-9, TIMP-3 and NADPH oxidase 4 (NOX4) were induced. Interestingly, they showed synergism between HHcy and hyperglycemia for endothelial-myocyte (E-M) uncoupling. Additionally, treatment with CZ alleviated MMP-9 activity and fibrosis, and improved EDD. On the other hand, treatment with tempol reversed cardiac remodeling in part by restoring the expressions of TIMP-3,-4, thioredoxin and MMP-9.</p> <p>Conclusions</p> <p>Endogenous homocysteine exacerbates diabetic cardiomyopathy by attenuating PPAR gamma and inducing E-M uncoupling leading to diastolic dysfunction. PPAR gamma agonist and tempol mitigates oxidative stress and ameliorates diastolic dysfunction in diabetes.</p