Stellar Metallicity Gradients in SDSS galaxies

We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ\_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data covers the central regions of these galaxies, out to slightly higher than $1 R_{e}$. We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. The gradients are only weakly dependent on stellar mass, and this dependence is well-correlated with the change of $R_e$ with mass. Based on this data, we report mean equivalent widths, metallicities, and abundance ratios as a function of mass and velocity dispersion for SDSS early-type galaxies, for fixed apertures of 2.5 kpc and of 0.5 $R_e$.Comment: 19 pages; 8 tables, 12 figures. Submitted to ApJ for publicatio

Monetary policy and natural disasters in a DSGE model: how should the Fed have responded to Hurricane Katrina?

In the immediate aftermath of Hurricane Katrina, speculation arose that the Federal Reserve might respond by easing monetary policy. This paper uses a dynamic stochastic general equilibrium (DSGE) model to investigate the appropriate monetary policy response to a natural disaster. We show that the standard Taylor (1993) rule response in models with and without nominal rigidities is to increase the nominal interest rate. That finding is unchanged when we consider the optimal policy response to a disaster. A nominal interest rate increase following a disaster mitigates both temporary inflation effects and output distortions that are attributable to nominal rigidities.Monetary policy - United States ; Natural disasters - Economic aspects

QCD resummation in the framework of supersymmetry

Motivated by current searches for electroweak superpartners at the Large Hadron Collider, we present precision predictions for pair production of such particles in the framework of the Minimal Supersymmetric Standard Model. We make use of various QCD resummation formalisms and match the results to pure perturbative QCD computations. We study the impact of scale variations and compare our results to predictions obtained by means of traditionally used Monte Carlo event generators.Comment: 4 pages, 2 figures, contribution to the proceedings of Moriond QCD 201

5 S,15 S-Dihydroperoxyeicosatetraenoic Acid (5,15-diHpETE) as a Lipoxin Intermediate: Reactivity and Kinetics with Human Leukocyte 5-Lipoxygenase, Platelet 12-Lipoxygenase, and Reticulocyte 15-Lipoxygenase-1.

The reaction of 5 S,15 S-dihydroperoxyeicosatetraenoic acid (5,15-diHpETE) with human 5-lipoxygenase (LOX), human platelet 12-LOX, and human reticulocyte 15-LOX-1 was investigated to determine the reactivity and relative rates of producing lipoxins (LXs). 5-LOX does not react with 5,15-diHpETE, although it can produce LXA4 when 15-HpETE is the substrate. In contrast, both 12-LOX and 15-LOX-1 react with 5,15-diHpETE, forming specifically LXB4. For 12-LOX and 5,15-diHpETE, the kinetic parameters are kcat = 0.17 s-1 and kcat/ KM = 0.011 μM-1 s-1 [106- and 1600-fold lower than those for 12-LOX oxygenation of arachidonic acid (AA), respectively]. On the other hand, for 15-LOX-1 the equivalent parameters are kcat = 4.6 s-1 and kcat/ KM = 0.21 μM-1 s-1 (3-fold higher and similar to those for 12-HpETE formation by 15-LOX-1 from AA, respectively). This contrasts with the complete lack of reaction of 15-LOX-2 with 5,15-diHpETE [Green, A. R., et al. (2016) Biochemistry 55, 2832-2840]. Our data indicate that 12-LOX is markedly inferior to 15-LOX-1 in catalyzing the production of LXB4 from 5,15-diHpETE. Platelet aggregation was inhibited by the addition of 5,15-diHpETE, with an IC50 of 1.3 μM; however, LXB4 did not significantly inhibit collagen-mediated platelet activation up to 10 μM. In summary, LXB4 is the primary product of 12-LOX and 15-LOX-1 catalysis, if 5,15-diHpETE is the substrate, with 15-LOX-1 being 20-fold more efficient than 12-LOX. LXA4 is the primary product with 5-LOX but only if 15-HpETE is the substrate. Approximately equal proportions of LXA4 and LXB4 are produced by 12-LOX but only if LTA4 is the substrate, as described previously [Sheppard, K. A., et al. (1992) Biochim. Biophys. Acta 1133, 223-234]

Revisiting slepton pair production at the Large Hadron Collider

Motivated by the shift in experimental attention towards electroweak supersymmetric particle production at the CERN LHC, we update in this paper our precision predictions at next-to-leading order of perturbative QCD matched to resummation at the next-to-leading logarithmic accuracy for direct slepton pair production in proton-proton collisions. Simplified models, now commonly adopted by the experimental collaborations for selectrons and smuons as well as mixing staus, are used as benchmarks for total cross sections at achieved and future center-of-mass energies. They are presented together with the corresponding scale and parton density uncertainties in graphical and tabular form for future reference. Using modern Monte Carlo techniques, we also reanalyze recent ATLAS and CMS slepton searches in light of our precision cross sections and for various assumptions on the decomposition of the sleptons and their neutralino decay products.Comment: 32 pages, 10 figures, 4 tables; version accepted by JHE

Associative memory stored by functional novel pathway rather than modifications of preexisting neuronal pathways

Associative conditioning involves changes in the processing pathways activated by sensory information to link the conditioned stimulus (CS) to the conditioned behavior. Thus, conditioning can recruit neuronal elements to form new pathways for the processing of the CS and/or can change the strength of existing pathways. Using a behavioral and systems level electrophysiological approach on a tractable invertebrate circuit generating feeding in the mollusk Lymnaea stagnalis, we identified three independent pathways for the processing of the CS amyl acetate used in appetitive conditioning. Two of these pathways, one suppressing and the other stimulating feeding, mediate responses to the CS in naive animals. The effects ofthese two pathways on feeding behavior are unaltered by conditioning. In contrast, the CS response ofa third stimulatory pathway is significantly enhanced after conditioning, becoming an importantcontributor to the overall CS response. This is unusual because, in most of the previous examples in which naive animals already respond to the CS, memory formation results from changes in the strength of pathways that mediate the existing response. Here, we show that, in the molluscan feeding system, both modified and unmodified pathways are activated in parallel by the CS after conditioning, and it is their integration that results in the conditioned respons

Understanding the effects of violent video games on violent crime

Psychological studies invariably find a positive relationship between violent video game play and aggression. However, these studies cannot account for either aggressive effects of alternative activities video game playing substitutes for or the possible selection of relatively violent people into playing violent video games. That is, they lack external validity. We investigate the relationship between the prevalence of violent video games and violent crimes. Our results are consistent with two opposing effects. First, they support the behavioral effects as in the psychological studies. Second, they suggest a larger voluntary incapacitation effect in which playing either violent or non-violent games decrease crimes. Overall, violent video games lead to decreases in violent crime. --Video Games,Violence,Crime

Taylor-type rules and total factor productivity

This paper examines the impact of a persistent shock to the growth rate of total factor productivity in a New Keynesian model in which the central bank does not observe the shock. The authors then investigate the performance of alternative policy rules in such an incomplete information environment. While some rules perform better than others, the authors demonstrate that inflation is more stable after a persistent productivity shock when monetary policy targets the output growth rate (not the output gap) or the price-level path (not the inflation rate). Both the output growth and price-level path rules generate less volatility in output and inflation following a persistent productivity shock compared with the Taylor rule.Taylor's rule ; Productivity ; Industrial productivity

The monetary instrument matters

This paper revisits the debate over the money supply versus the interest rate as the instrument of monetary policy. Using a dynamic stochastic general equilibrium framework, the authors examine the effects of alternative monetary policy rules on inflation persistence, the information content of monetary data, and real variables. They show that inflation persistence and the variability of inflation relative to money growth depend on whether the central bank follows a money growth rule or an interest rate rule. With a money growth rule, inflation is not persistent and the price level is much more volatile than the money supply. Those counterfactual implications are eliminated by the use of interest rate rules whether prices are sticky or not. A central bank's use of interest rate rules, however, obscures the information content of monetary aggregates and also leads to subtle problems for econometricians trying to estimate money demand functions or to identify shocks to the trend and cycle components of the money stock.Monetary policy ; Money supply ; Interest rates